: something that fills up, completes, or makes better or perfect
- The scarf is a perfect complement to her outfit.
: the full quantity, number, or assortment needed or included
- … the usual complement of eyes and ears …
- —Francis Parkman
- … after several more minutes of waiting, the full complement of runners was sent off by the starter's pistol.
- —Craig Neff
: the whole force or personnel of a ship
: one of two mutually completing parts : counterpart
- She is a kind of complement to me, and we get on famously.
- —Flannery O'Connor
: an added word or expression by which a predication is made complete (such as president in "they elected him president" and beautiful in "he thought her beautiful")
: the angle or arc that when added to a given angle or arc equals a right angle in measure
: the set of all elements that do not belong to a given set and are contained in a particular mathematical set containing the given set
: a number that when added to a certain number of the same sign yields a number with the digit 1 as the significant digit farthest to the left and the digit 0 in every other digit place
—used especially in assembly language programming
: the musical interval required with a given interval to complete the octave
: the thermolabile group of proteins in normal blood serum and plasma that in combination with antibodies causes the destruction especially of particulate antigens (such as bacteria and foreign blood corpuscles)