h₁ey-tó-
“gone, departed, past”exit, perish, transit, obituary
Participial of *h₁ey- giving Latin exitus > exit, perīre > perish, transitus > transit.
Discussion
The PIE form *h₁ey-tó- (gone, departed) is a past participle from the root *h₁ey- (to go), formed with the participial suffix *-tó-. The meaning is "having gone" — the state of being departed, past, no longer present. From this participle of going, multiple IE languages built their vocabularies for death, departure, and temporal passage.
Latin exīre (to go out) produced exit — the going-out, the departure from a stage, a building, or a life. The noun exitus (a going out, a departure, a death) is used in medical Latin for the moment of death: exitus letalis, the lethal going-out. English exit preserves both the theatrical and the terminal senses.
Latin perīre (to go through, to be destroyed, to perish) makes the connection between going and dying explicit: to perish is to go through completely, to pass through existence to its end. The derivative perishable (liable to perish) applies the root to food, materials, and all transient things.
Latin transīre (to go across) gave English transit, transition, and transient — all forms of going-across, of passage from one state to another. The grammatical term transitive (a verb that "goes across" to affect an object) preserves the metaphor in linguistic terminology.
Latin obīre (to go toward, to go to meet — especially to meet one's death) produced obituary: the record of someone's going-toward-death, their final departure. The euphemistic quality is characteristic of IE death vocabulary: rather than naming death directly, the word describes the approach, the going-toward.
The root *h₁ey- itself is one of PIE's fundamental motion verbs, distinct from *gʷem- (to come) and *h₃ey- (to go on a journey). The three roots divided the semantic space of locomotion: *h₁ey- was the bare act of going, *gʷem- was arriving/coming, and *h₃ey- was purposeful journeying. The past participle *h₁ey-tó- captured the completed going — and from that completion, daughter languages derived their concepts of departure, death, and the passage of time.