I told you yesterday.
yellowing
a four letter word starting with Y could be: Yolk (as in an egg yolk) Yack Yarn Yawn York
Some four letter words that start with Y are:yankyardyarnyawnyeahyearyellyelpyipeyogayokeyolkyoreyouryowlyuckyuleyurt
ApologyOthers include:abilityacidityactuaryagilityallergyamenityamiablyanalogyanatomyanchovyangrilyanomalyatrophy
How about "density"?
Yews
yelling
yak
No word starting with the letter y contains the letter x.
a four letter word starting with Y could be: Yolk (as in an egg yolk) Yack Yarn Yawn York
Yummy
young
There is no such word in the English language.
Yardworks :D
complying
Some four letter words that start with Y are:yankyardyarnyawnyeahyearyellyelpyipeyogayokeyolkyoreyouryowlyuckyuleyurt
It is every.
Oh, dude, the longest word starting with the letter Y is "yttrium." It's like 7 letters long, so I hope you have the energy to say it all in one breath. But hey, at least now you can impress your friends at your next Scrabble game with your knowledge of obscure Y words.