A person who contributes to the fulfillment of a need or furtherance of an effort or purpose:
— My invaluable assistant.

synonyms: help, helper, supporter.

Roget 711: auxiliary; recruit; assistant; adjuvant, adjutant; ayudante^†, coaid^†; adjunct; help, helper, help mate, helping hand; midwife; colleague, partner, mate, confrere, cooperator; coadjutor, coadjutrix^†; collaborator.    ally; friend etc. 890, confidant, fidus Achates [Lat.], pal, buddy, alter ego.    [criminal law] confederate; accomplice; complice; accessory, accessory after the fact; particeps criminis [Lat.]; socius criminis [Lat.].    aide-de-camp, secretary, clerk, associate, marshal; right-hand, right-hand man, Friday, girl Friday, man Friday, gopher, gofer; candle-holder, bottle-holder; handmaid; servant etc. 746; puppet, cat's-paw, jackal^†.    tool, dupe, stooge, ame damnee [Fr.]; satellite, adherent.    votary; sectarian, secretary; seconder, backer, upholder, abettor, advocate, partisan, champion, patron, friend at court, mediator; angel (theater, entertainment). friend in need, Jack at a pinch, deus ex machina [Lat.], guardian angel, tutelary genius.    ... show more

Dutch: assistent, helper, hulp, dienstknecht, knecht, waterdrager
Polish: pomagier, pomocnik

Of or relating to a person who is subordinate to another.

synonym: adjunct.