Synonyms: supplemental, supplementary
Definition: added to complete or make up a deficiency
Usage: produced supplementary volumes
Synonyms: subsidiary, supplemental, supplementary, auxiliary
Definition: functioning in a supporting capacity
Usage: the main library and its auxiliary branches
Similar words: secondary
Definition: being of second rank or importance or value; not direct or immediate
Usage: the stone will be hauled to a secondary crusher; a secondary source; a secondary issue; secondary streams