Synonyms for Trendy:

adj.

all (adjective)
voguish.
far-out (adjective)
modernistic.
fashionable (adjective)
swank, stylish, trig, in, all the rage, Tony, modish.
in fashion, style (adjective)
swank, popular, with-it, in, voguish, up-to-the-minute, stylish, modish, fashionable, contemporary, Tony.
plush (adjective)
swanky.
sharp (adjective)
sharp.
stylish (adjective)
contemporary, popular.

n.

modernistic, modern, space age, advanced, ahead of your/its etc. time, state of the art, futuristic. sharp, dandy, clotheshorse, Tony, mod, a la mode, snappy, in, dweeb, style, swanky, dresser, dag, fop, dashing, classy, beau, trig, modish, coxcomb, swish, blade, swank, posh, all the rage, usual, up-to-the-minute, with-it, metrosexual. trendy (noun)
fashionable, voguish, stylish.

Other synonyms:

mod, Tony, trig, popular, classy. posh. dashing, snappy, modish. in. sharp. up-to-date
modern, with-it.
Other relevant words:
popular, clotheshorse, trig, mod, blade, dashing, futuristic, snappy, Tony, modernistic, usual, contemporary, classy, dweeb, posh, style, metrosexual, beau, coxcomb, swank, all the rage, with-it, swish, dresser, space age, dag, modern, dandy, swanky, in, fop, state of the art, modish, sharp, up-to-the-minute, advanced.