1 robber, burglar, cat burglar, housebreaker, picklock, sneak-thief, safe-cracker, pilferer, shoplifter, purloiner; embezzler, peculator; pickpocket, cutpurse, purse-snatcher, mugger, highwayman, footpad, brigand, bandit, thug, dacoit, ruffian, outlaw, desperado, hijacker, gunman, plunderer; poacher; Technical kleptomaniac, Australian bush-ranger, US road-agent, Colloq hold-up man, crook, US second-story or second-storey man, bandito or bandido, Slang cracksman, box man, dip, stick-up man:
They caught the thief who took the paintings.
2 cheat, swindler, confidence man, mountebank, charlatan, sharper, trickster, flimflam artist or man, thimblerigger, Colloq con man, con artist, shell-game artist, US highbinder:
That thief cheated them out of their savings.
3 pirate, (sea) rover, picaroon or pickaroon, corsair, freebooter, buccaneer, marauder, filibuster, privateer:
They might seem romantic in retrospect, but at the time, pirates were no more than common thieves.