Just a heads up ^-^ A Japanese word of the day may or may not be posted on Saturdays -- if it is, it's going to have to be a lot later. Which also means I have to get back to any comments or questions later as well.

does korosenai mean unkillable then?

does korosenai mean unkillable then?

Sorry for having to get back so late. すみません！^~^ 殺せない(korosenai) doesn't mean unkillable nor is it an adjective. 

殺せない is a conjugation of the verb 殺す(korosu), which means to kill. What 殺せない meaning is "Can not kill." However, verbs can modify nouns much like adjectives. If you modified a noun --　say 人(hito; person) -- with the verb 殺せない it would mean "Person that can not kill. (殺せない人)" Which isn't what you're aiming for.

 To say something along the line of unkillable, I would just use an adjective like ふじみ（な） (fugimi na; immortal) to convey the same meaning. For example, ふじみな人, "Immortal person." The reason I feel this is better is because of this: 殺されることができない人(korosareru koto ga dekinai hito)! That's just plain clunky, lol. I kind of opened a pandora's box of grammar with this, haha. I hope I didn't go overboard. Anywho, I hope this helped. ^-^