yelling
yak
No word starting with the letter y contains the letter x.
The longest word with y in it is Rythms. sorry if that dissapoints you.
a four letter word starting with Y could be: Yolk (as in an egg yolk) Yack Yarn Yawn York
Yummy
young
Some four letter words that start with Y are:yankyardyarnyawnyeahyearyellyelpyipeyogayokeyolkyoreyouryowlyuckyuleyurt
It is every.
ApologyOthers include:abilityacidityactuaryagilityallergyamenityamiablyanalogyanatomyanchovyangrilyanomalyatrophy
I told you yesterday. yellowing
How about "density"?