... Contraction of Latin ore rotundo (with a round mouth), from ore, from os (mouth) + rotundo, from rotundus (round), from Indo-European root ret- (to run or roll) Other words derived from the same ... on opposite sides of a common axis From Latin pinnatus (feathered), from pinna (feather), ultimately from Indo-European root pet- (to rush, fly) Other words from this root are pin, impetus, and ... Susceptibility to change, lapse, error, or instability From French/Middle English from Late Latin labilis (prone to slip), from labi (to slip) Other words from the same root are avalanche, lapse, and lava...