in algebra, are such numbers, or known quantities, as are put before letters or quantities, whether known or unknown, and into which they are supposed to be multiplied. Thus, in $3x$, $ax$, or $bx$; $a$ and $b$, are the coefficients of $x$; and in $6a$, $9b$; $6$, and $9$, are the coefficients of $a$ and $b$. See ALGEBRA.