Main definitions of y in US English:

: y1Y2Y3

y1

abbreviation

• Year(s)

‘orbital period (Pluto): 248.5y’

/yes//jɛs/

: y1Y2Y3

Y2

(also y)

noun

• 1The twenty-fifth letter of the alphabet.

• ‘Created by two of todays wittiest, most imaginative minds, The Alphabet from A to Y with Bonus Letter Z! is a sheer delight from A to Z.’
• ‘Find fun games, crafts, stories, and other educational activities all related to the letter Y.’
1. 1.1 Denoting the next after X in a set of items, categories, etc.
• ‘After Boomers and X's, Here Come the Y's.’
• ‘What Comes Next After Generation X? ... I would say, generation Y.’
2. 1.2 Denoting a second unknown or unspecified person or thing.
‘the claim that chemical X causes birth defect Y’
• ‘In mathematics, Y is the second in a set of two or three unknowns comprising x, y, and z.’
• ‘Y denotes a second unknown or unspecified person or thing: the claim that chemical X causes birth defect Y.’
3. 1.3usually "y" The second unknown quantity in an algebraic expression, usually the dependent variable.
• ‘In algebra, a variable is a symbol used to represent any number. For example, in this equation:. 2(x+y) = 2x + 2y. x and y are variables.’
• ‘By convention, we call the dependent variable y.’
4. 1.4usually "y" Denoting the secondary or vertical axis in a system of coordinates.
in combination ‘the y-axis’
• ‘The horizontal axis is normally labeled x, and the vertical axis is normally labeled y.’
• ‘Cartesian coordinate system with the circle of radius 2 centered at the origin marked in red. The equation of the circle is x2 + y2 = 4..’
• 2"Y"A shape like that of a capital Y.

in combination ‘rows of tiny Y-shaped motifs’

: y1Y2Y3

Y3

abbreviation

• 1Yen.

‘Y140’
• 2North American informal A YMCA, YWCA, YMHA, or YWHA facility.

‘Scott was living at the Y’
• ‘Its Fun To Stay At The Y in HK.’
• ‘With the intensity of the heat and the humidity becoming all a little too much, I came back to the Y, for a swim and for a sleep.’
• The chemical element yttrium.

/waɪ//wī/