c. 1300, yolpen, probably echoic variant of yelpen (see yelp). Related: Yawped; yawping. The noun, in reference to speech, is recorded from 1835, now used chiefly in conscious echo of Whitman (1855).
yarrow
yaw
yawl
yawn
yawner
yawp
yaws
yay
yclept
ye
*ye-