XV = XIV
Roman numeral
or
XV = XUV
extreme ultraviolet radiation
XV = XIV
Roman numeral
or
XV = XUV
extreme ultraviolet radiation
XW = xaw, The Athena Widget Set.
XX - Xerox
XY = xerography
XZ = Xbiz, news outlet for adult-rated media.
YA: ytterbia
YB - yob
YC = yonic
YD = yodeled
YE - Yosemite
YF = yourself
yg - young
YH - yeah
YI: yogi (practitioner of yoga)
YJ = yaj – seven definitions in the Urban Dictionary.
YK - yak
YL = yodel
YM: yum!
YN: yearn
YO - yo-yo