noun
or coordinate covalence
: a covalent bond typical of coordination complexes that is held to consist of a pair of electrons donated by only one of the two atoms it joins [as in the compound (C 2 H 5 ) 3 N:BF 3 formed from triethylamine (C 2 H 5 ) 3 N: and boron fluoride BF 3 ] — called also dative bond, semipolar bond