The word translated 'thieves' for the two men crucified beside Jesus, and 'robber' for Barabbas. It means something more dangerous.
Documented
The lexicon and the penalty agree
Lestes in Greek means bandit, brigand, or rebel, the same word Josephus uses for anti-Roman insurgents. Rome reserved crucifixion for slaves and insurrectionists; ordinary theft did not merit it. Scholars including Horsley and Hanson documented the social-bandit phenomenon: lestai as peasant resistance, not mere crime. Barabbas is explicitly called a lestas imprisoned with rebels.
Assessment: Fully documented in the lexica, in Josephus, and in Roman legal practice. The mismatch between 'thief' and the capital punishment is a standard point in the scholarship.
Stories
The good thief got a promotion
The tradition softened the scene: the penitent thief, Dismas in later naming, confesses and is promised paradise. Crucifixes and sermons made the two men emblematic sinners, one saved, one lost. The political charge of the word faded as the devotional story grew.
Assessment: Documented as the tradition's development: the names, the iconography, the sermon tradition all postdate the text. The word never changed; the story around it was domesticated.
Interesting claims
Hillman's trafficker gloss
Ammon Hillman pushes the word further: lestas as trafficker, specifically of children, folding the crucifixion scene into his broader thesis of an ancient trade the texts record and translators hide. The claim circulates widely through podcast appearances.
Assessment: No lexicon supports the trafficking gloss for lestes; Hellenists have rebutted it directly and in detail. What the rebuttals cannot remove is the documented core: the word means insurgent, the punishment fits insurgency, and 'thieves' is a translation choice that shrinks a political execution into a crime scene. That shrinkage needs no fringe theory to be interesting.
Sources and further reading
Josephus, Jewish War 2.253-254, lestai as insurgents
If the word marks all three as political insurgents, was the scene in the middle a lynching of thieves, or an execution of revolutionaries, and who needed the smaller story?