The word 'suicide' is a modern Latin formation from the 17th century, created by combining the Latin reflexive pronoun 'sui' (of oneself) with the English combining form '-cide', which denotes killing. The Latin root 'caedere' (to cut down, strike, kill) is of Proto-Indo-European origin, related to concepts of striking. This construction follows the pattern of other '-cide' words like 'homicide' (killing of a man) and 'fratricide' (killing of a brother), but uniquely applies the act reflexively to the self. The term's logic is transparently literal—'self-killing'—and its adoption filled a lexical gap, as earlier English used phrases like 'self-murder' or 'self-slaughter'.

Structure: sui (of oneself) + cide (act of killing) sui is a Latin reflexive pronoun meaning 'of oneself'. cide is an English combining form from Latin '-cidium' (act of killing) and '-cida' (killer), derived from the verb 'caedere' (to cut, to strike, to kill).