I came across this word "こうかん" that was defined as "exchange; substitution." An example sentence was given as:
ちゅうこしゃ を うって しんしゃ と こうかんした。
It looks like こうかん is used as, and conjugated as a verb. Since I thought all dictionary forms of verbs end in U, how does this one not? Could it be in a conjugated form already, even though it doesn't look like a conjugation?
This is actually a noun + する pair. There are many nouns that can have する added to them to "verbify" them. Well, in truth you're adding をする、then dropping the を because it's understood by context—sometimes the を will be left in for emphasis.
So こうかん(交換) is a noun meaning, as you say, "exchange; substitution", and 交換する or 交換をする means "to exchange; to substitute".



I didn't think of that. I figured that the sample sentence would give the use in the sentence the same way they defined it, namely not as a verb. Arigatou gozaimasu!
Yosh!