ǵerh₂-
“to cry out, to call”cry, shout, call
Root for crying out, yielding Latin grex/gregis (flock, called together), English crane, crack.
Discussion
The PIE root *ǵerh₂- (to cry out, to call, to sing loudly) produced the vocabulary of vocal clamour — the raised voice of alarm, proclamation, and celebration.
Latin garrīre (to chatter, to babble) may connect, though the derivation is debated. More securely, the root appears in the IE vocabulary of cranes and other loud-calling birds — Greek géranos (γέρανος, "crane") names the bird by its cry, and the word crane itself (OE cran, from PGmc *kranô) may descend from the same root through the concept of "the crying one."
The crane connection extends into an unexpected domain: the mechanical crane (the lifting device) is named after the bird because its long arm resembles the bird's neck. So a PIE root for crying out generated the name of a loud bird, which generated the name of a construction machine.
Old Irish gáir ("a cry, a shout") preserves the Celtic reflex directly. Lithuanian gerdù ("I praise, I cry out") confirms the Baltic form.
The root belongs to the PIE vocabulary of loud vocalization: compare *sengʷʰ- (to sing — melodic voice), *ḱens- (to proclaim formally), *gʰeh₁- (to invoke ritually), and *weḱ- (to speak ordinarily). *ǵerh₂- apparently occupied the register of unrestrained vocal force — the shout, the cry, the call across distance.
Notes
Pokorny 383. English crane, crack, crow, congregation, gregarious.