YK: tyke.
YL: Carboxylic
YM: rhyme.
YN = dynamo
YO: playoff.
YO = young
YP: Cyprus
YQ = Nyquil
YR = gyrate
YS: Days
YT: myth.
YU = yucca
YV: MacGyver.
YW: jaywalking
YX: coccyx.
YY - Khmelnytskyy
YZ: Byzantine.
ZA: stanza
ZB - whizzbang
ZC: Ezcurrite (a borate mineral).