noun
or Y /ˈwaɪ/ , pl y's or ys or Y's or Ys /ˈwaɪz/
the 25th letter of the English alphabet [count]
[noncount] mathematics - used to represent especially a second unknown quantity
[noncount] - used in the phrase x, y, and z to refer to the second thing in a group of three unnamed things
[count] :something that is shaped like a Y
the Y US informal :the YMCA or the YWCA