I was adjusting my definition of fruitarianism for 20 years, periodically changing it after reflecting on what I learned and experienced. You can read it on the top of the page, and the current version is this: 

Fruitarianism - a quest for optimal ethical ways to live and diets based on fruits and seeds. 

This is the line I just attempted to add to the definition of fruitarianism on the Wikipedia page: 
"Fruitarianism can also be viewed as a set of ethical values, including respecting the lives of plants, and their implementation in lifestyle." But I could not find eligible resources to cite.

Wiki is the most popular resource online, and the article dedicated to fruitarianism requires some explanation for most people who are new to the term. In this article, I will also give my personal perspective as a practicing skeptic fruitarian.

Definitions of Fruitarianism

Fruitarianism

I live and write about fruitarian ethics, history, worldview and ideas - theoretical and cultural aspects of fruitarianism, fruitarian lifestyle and diet. 

Fruitarian ethics: moral principles that govern a fruitarians' behavior, fruitarian moral code, fruitarian values and value system, ideals, fruitarian standards of behavior, fruitarian virtues and conscience.

Fruitarianism /fruːˈtɛəriənɪzəm/ :

• a diet that consists entirely or primarily of fruits in the botanical sense, and possibly nuts and seeds, without animal products;
• a philosophy of non-harming living organism without need, especially animals and plants;
• a lifestyle that reflects these ethical and environmental values.

Main Definition 

Analysis of definitions of fruitarianism from Wikipedia, with citations, followed by agreement statements, commentary, and objections. 

Fruitarianism (/fruːˈtɛəriənɪzəm/) is a diet that consists entirely or primarily of fruits in the botanical sense, and possibly nuts and seeds, without animal products. Fruitarianism is a subset of dietary veganism.

1. Yes. Fruitarian diet consists primarily of fruits in the botanical sense (including non-sweet fruits like tomatoes, avocados, and many other fruit-vegetables), with added seeds (including nuts, beans, and often grains), but often also some leafy greens, mushrooms, algae, etc.
2. Yes / No. It almost never consists of fruit only, without any seeds or other additions. I heard about a couple of people who supposedly followed such diet, but it was never clarified by themselves that they actually did, for how long, and how they avoided tiny embedded seeds in many types of fruit like strawberries. 
3. No. Fruitarianism is not only a diet - in most cases it is rather a set of ethical principles, reflected in lifestyle, including diet.
4. Yes / No. Only as a diet could fruitarianism be viewed as a subset of dietary veganism, and not in all cases. Some fruitarianism consider some animal foods ethical (e.g. eggs under certain circumstances). From philosophical perspective, veganism is a subset of fruitarianism, because fruitarians take to consideration lives of other living organisms, which do not necessarily belong to animal kingdom (Animalia or Metazoa).

Reasons

Fruitarianism may be adopted for different reasons, including ethical, religious, environmental, cultural, economic, and health reasons. There are many varieties of the diet. Some people whose diet consists of 75% or more fruit consider themselves fruitarians.

• Yes. All these statements are true. 

Some fruitarians will eat only what falls (or would fall) naturally from a plant: that is, foods that can be harvested without killing or harming the plant.

• Yes. Harvesting fruits and seeds, which are created by plants to be eventually separated from the plant organism, and though not causing the death or severe damage to the plants, is the main reason for choosing this diet by ethical fruitarians, and also frugans. 

These foods consist primarily of culinary fruits, nuts, and seeds.

• Yes/No. True fruits botanically speaking are not all considered culinary fruits. They are classified as vegetables in the culinary sense (eggplant, zucchini, cucumbers, etc.), but undoubtedly accepted by most fruitarians.

Some do not eat grains, believing it is unnatural to do so, and some fruitarians feel that it is improper for humans to eat seeds as they contain future plants, or nuts and seeds, or any foods besides juicy fruits.

• Yes. There are fruitarians who do not eat grains, because they believe that most grains are not well digestible. Many others, though, eat grains soaked or sprouted for that reason. Most people with such views, I met over the years, are raw-foodist or natural-hygienists, and concerned primarily about health and bodily purity of some sort. 
• Yes. Over the years I had multiple debates with fruitarians who avoid eating any seeds, and most of them had religious reasons to do so. Some had allergies towards nuts. Plants usually produce seeds in abundance without harming themselves, and only a small part of the seeds have possibility to grow, if any. That's why many animals, including humans, use seeds as nourishment, and in some cases increase the chances of the seeds to develop into a plant by doing so.  

Others believe they should eat only plants that spread seeds when the plant is eaten.

This is a poorly expressed idea. I guess, it should be about eating seeds only of the plants that evolutionary develop to rely on animals to spread the seeds, by eating fruit with the small seeds in the flesh, and the seeds are not destroyed by digestion. I know the idea, but I have not talked with a person who actually follows it. 

Others eat seeds and some cooked foods.

This description could fit many dietary approaches, not only fruitarians. The "cooked foods" placed here in one broad category and can include practically anything. 

Some fruitarians use the botanical definitions of fruits and consume pulses, such as beans, peas, or other legumes. Other fruitarians' diets include raw fruits, dried fruits, nuts, honey and olive oil, or fruits, nuts, beans and chocolate.

Yes. This are accurate statements. 

Some fruitarians who espouse Judeo-Christian beliefs hold that fruitarianism was the original diet of humankind in the form of Adam and Eve, based on an uncommon interpretation of the Book of Genesis 1:29. They believe that a return to an Eden-like paradise will require simple living and a holistic approach to health and diet.

Yes. I personally know several people with this motivation. Unfortunately, they do not participate in fruitarian conversation anymore, and some seem to have abandoned the diet. 

Some fruitarians wish, like Jains, to avoid killing anything, including plants, and refer to ahinsa fruitarianism.

Yes. For example, my personal initial motivation is of the same nature. I am a non-religious person, but the philosophical ideas of that tradition of thought had the most impact on me. 

Ahimsa (Sanskrit: अहिंसा; IAST: ahimsā, Pāli: avihiṃsā) is a term meaning 'not to injure' and 'compassion'.

Some fruitarians say that eating some types of fruit does the parent plant a favor and that fleshy fruit has evolved to be eaten by animals, to achieve seed dispersal.

Frugivores can either benefit fruit-producing plants by dispersing seeds, or they can negatively affect plants by digesting seeds along with the fruits. When both the fruit-producing plant and the frugivore species benefit by fruit-eating behavior, their interaction is called mutualism.

For some fruitarians, the motivation comes from a fixation on a utopian past, their hope being to return to a past that predates an agrarian society, to when humans were simply gatherers.

Yes. This motivation is very prominent among fruitarians I know or was ever connected to. Many times I was invited to live in a fruitarian commune in a remote location, and some of similar projects are still active. 

Another common motivation is the desire to eliminate perceived toxicity within the body. For others, the appeal of a fruitarian diet comes from the challenge that the restrictive nature of this diet provides.

Yes. I believe these statements to be true. 

Updates

It seems to be difficult to add any notion of ethics to the main definition of fruitarianism on Wikipedia: https://en.wikipedia.org/wiki/User_talk:Fruitarianlena

I supported this encyclopedia financially, it is one of the greatest projects on the internet, but in case of fruitarianism good accepted resources are hard to find, and the existing are somewhat questionable to me. If anyone knows an independent non-fruitarian author who have non-self-published materials, mentioning fruitarian ethics, please let me know.