From Latin 'flagrāre' (to burn), from PIE *bʰleg- — 'in flagrante delicto' means 'caught while the crime still blazes.'
Conspicuously or obviously offensive; shockingly noticeable, usually of wrongdoing.
From Latin 'flagrantem,' the present participle of 'flagrare' (to burn, to blaze, to glow with heat or passion), from PIE *bʰleg- (to burn, to shine, to gleam with intense heat or light). This root is among the most widely attested in the Indo-European family. Through the Latin branch: 'flamma' (flame), 'fulgor' (lightning, brilliance), 'fulgere' (to shine, to flash), 'conflagrare' (to burn entirely),
The legal phrase 'in flagrante delicto' (caught in the burning offense) literally means caught while the crime is still 'on fire' — so fresh and blatant that it blazes. The phrase is commonly shortened to 'in flagrante,' especially in the context of catching someone in an act of adultery.