Re: flies ?
Here are my definitions of pattern types:
dry fly - a pattern, fished on the surface, which imitates the adult (terrestrial) lifestage of an aquatic insect
emerger - a pattern, fished on the surface (on its immediate proximity), which imitates transition from an aquatic (nymphal or pupal) to the adult (terrestrial) lifestage of an aquatic insect
wet fly - a pattern, fished subsurface (usually in the top half of the water column), which is sufficiently generalized to not closely resemble any particular aquatic insect (in other words a subsurface attractor)
nymph - a pattern, fished in the general proximity of the bottom, which imitates the nymphal lifestage of an aquatic insect
attractor - a pattern, generally a dry fly, which doesn’t resemble any specific insect closely enough to be considered an imitation of it, but that (perhaps) resembles many insects closely enough to interest trout
streamer – a pattern, fished subsurface, which is usually intended to imitate baitfish