古英语 þeof “一个通过秘密手段从他人那里窃取财物的人;强盗”,来自原始日耳曼语 *theuba-(也源自古弗里西亚语 thiaf,古撒克逊语 thiof,中世纪荷兰语和荷兰语 dief,古高地德语 diob,德语 dieb,古诺尔斯语 þiofr,哥特语 þiufs),一个起源不确定的词。
在中英语中也指偷猎者、骗子、海盗、自夸者、高利贷者,对不法和欺诈行为者的普遍指责。Den of thieves “不法之徒的居所”源自14世纪晚期(dennes of þeves),早期短语为 thieves' ditch(theovesdiches,约公元1100年)。
A thief takes other people's property without their knowledge ; a robber takes it openly, whether or not resistance is offered : in a looser sense, thief is often applied to one who takes a small amount, and robber to one who takes a large amount. [Century Dictionary, 1895]