Does the word "collidee" exist?

It's not entirely uncommon for English speakers (and I suspect this is true for speakers of other languages) to invent words for one time use. I myself have done this using the -er /-ee suffix pattern. Using Employer/Employee as an example, the suffix -er applies to someone or something performing an action in this case providing employment, and the -ee suffix applies to the person or thing the action is being applied to. So hypothetically you could use the word collidee given a certain context, but you will not find this word in a dictionary, and a native speaker would likely not understand what you mean without additional context.

No, but it would be understood (and perhaps funny) in the right context. "I was involved in a vehicular collision, but the other driver was the colliDER and I was the colliDEE." (You are stating that the other driver hit YOU) Note the emphasis, and the fact that it is used right next to the other form(s).

It does now, lol... that's the thing about English, if you coin or manipulate a word in a way that is clearly understood and makes sense in context, it's a valid word, even if it's not widely known or recognized. You (probably) won't find "collidee" in any dictionary (and I wouldn't recommend trying to get away with it in Scrabble), but clearly it means "one who has been struck or collided with" implying that the other party was in motion/caused/failed to avoid the collision.

No, it's not a real word

No.

It is not in the Oxford English Dictionary. Only, --- collided, adj. 1657– Of two or more things: that have collided; (of a… colliding, adj. 1694– That collides (in various senses of collide, v.). colliding, n. 1849– The action of collide, v. (in various senses)… collider, n. 1963– Particle Physics. An accelerator in which two… --- I would probably write, "The person he collided with". Depending on the context.

It sounds funny, like haha funny. I don't know if it's a real word, but the thing about languages is you can kind of just make words up, and as long as you do it in the right context, where you are clearly understood, people may receive it well. If you said something such as "the large hadron collider works nonstop, colliding unwitting particle-sized collidees into each other" this sounds kind of cute and amusing to me. Like something a humorous, entertaining Youtuber might say.

No. It’s problematic because the primary meaning of collide connotes an accidental collision. “I collided with a wall” - I didn’t intend to do this. Other nouns like this - Invitee. Trustee. Attendee. Employee. Trainee. Etc. are all the recipient of an intentional action. Further. The alternative meaning - cause two things to collide - needs two objects. The LHC causes two particle to collide. Two collidees?

Not technically, but native speakers blend words and suffixes together to form new words all the time, often because it is technically wrong and thus can be funny. So yeah, people would know what you mean as long as it was used in a context where a collision was already the topic at hand.

I don’t think it’s a word on the sense of it being in the dictionary, but as far as I know any transitive verb that can take a “er” can take an “ee”.

It's not a word, but it would be understood by native speakers. ee/er is understood to be the relationship between do-er and do-ee. Sender (a word) sendee (not a word, but understood)

The only way I’ve seen collider used is for the scientific equipment. All the collisions take place within it - it doesn’t collide with something else

if you're having trouble with this syntax you can just refer to the second person as "the person who collided"

It follows the common pattern so a native speaker would be able to suss it out but you could live many lifetimes and never encounter that word.

It's a bit unorthodox, but why not.

You may see it in informal English from time to time. Here's a complaint in an forum about Unity (a program used for creating video games): [Collisions seem to destoy both collider and collidee (or not!)](https://discussions.unity.com/t/collisions-seem-to-destoy-both-collider-and-collidee-or-not/461248) You're not likely to see *collidee* unless the word *collider* is mentioned (or at least heavily implied) and [you're not supposed to use "collidee" in Scrabble](https://scrabble.merriam.com/finder/collidee). If you use *collider* and *collidee* together, you'll probably be understood. Just don't do that in English class.