Other forms: widths
The noun width means the measurement of an object from one side to the other. The width of your twin bed is less than the width of your parents' queen-sized bed.
When you're talking about the dimensions of something, specifically how wide it is, you're discussing its width. The width of your backyard might not lend itself to a full croquet court, but you can still play horseshoes back there. And the width of the streets in some Midwestern cities might surprise you if you're used to narrow New England roads. Before the word width gained popularity in the 1620s, people used the now less common wideness instead.