h₁ey-
“to go, to walk, to move”go, walk
Root for going, yielding Latin ire, Greek eimi, Sanskrit eti.
Discussion
The PIE root *h₁ey- (to go, to walk, to move) is one of the most fundamental motion verbs in the reconstructed vocabulary — the bare, unmodified concept of going, distinct from *gʷem- (to come/arrive) and *steyǵʰ- (to climb). The root's simplicity made it extraordinarily productive: every language needs a word for going, and *h₁ey- filled that need across the family.
Latin īre (to go) continues the root as one of the most irregular but most essential Latin verbs. Its compounds pervade English: exit (ex-īre, "to go out"), transit (trans-īre, "to go across"), ambition (amb-īre, "to go around" — canvassing for votes), circuit (circum-īre, "to go around"), initial (initium, "a going in" — a beginning), obituary (obitus, "a going toward" — death as the final approach), perish (per-īre, "to go through" — to be destroyed), sedition (sed-itiō, "a going apart" — revolt), and the grammatical term transitive (a verb that "goes across" to an object).
The past participle itus gave English the suffix -ition/-ition in dozens of abstract nouns: transition, perdition, ambition, sedition, condition (con-dītiō, originally "a going together" — an agreed term).
Greek eîmi (εἶμι, "I go" — distinct from eimí, "I am") preserves the root in the Hellenic branch with a different conjugation. The Greek forms are attested throughout classical literature.
Sanskrit éti ("he goes") and the related áyana- ("way, path, course") continue the root in Indo-Iranian. The Buddhist term Mahāyāna ("great way") and Hīnayāna ("lesser way") deploy this root at the highest level of religious discourse.
Old Irish ethaid ("he goes") and Lithuanian eĩti ("to go") confirm Celtic and Baltic attestation. Old Church Slavonic iti ("to go") continues the Slavic reflex — Russian idtí is the direct descendant.
The root's presence in every major branch with the same meaning makes it one of PIE's most secure reconstructions. Its irregularity in many daughter languages — Latin īre is highly suppletive, Greek eîmi is defective — reflects its extreme age: the most basic verbs are often the most irregular, because they have been in continuous use long enough to accumulate centuries of analogical and phonological anomalies.
Notes
Pokorny 293-297. One of the most basic motion verbs in PIE.