Trap is not an adjective any more than any noun is an adjective. Almost all nouns can be used to modify other nouns. You can say a kitchen sink, a faculty office, and a soccer ball. That doesn't make kitchen, faculty, and soccer adjectives. I understand that en.wikt has trap as an adjective, but that is an error. Feel free to correct it.
Most adjectives can be modified by very. Most adjectives have a comparative form. Most adjectives can function as complements to seem. But you can't say something is very trap or trapper. Nor can you say something seemed trap.--Brett (talk) 12:49, 18 February 2010 (UTC)