Someone who's larcenous has a tendency to steal things. You can describe a classmate as larcenous if she proudly shows off the candy she's stolen from the corner store.
Pickpockets, car thieves, and politicians who accept bribes are all larcenous — they are all motivated by a desire for financial gain and a willingness to take things that don't belong to them. This adjective comes from larceny, a fancy way to say "theft." Both words have their roots in the Latin latrocinium, "robbery," which comes from latro, "robber or bandit."