ben ‧ e ‧ fi ‧ cial AC /ˌbenəˈfɪʃ ə l◂, ˌbenɪˈfɪʃ ə l◂/ BrE AmE adjective
[ Word Family: noun : ↑ benefit , ↑ beneficiary ; verb : ↑ benefit ; adverb : ↑ beneficially ; adjective : ↑ beneficial ]
[ Date: 1400-1500 ; Language: Latin ; Origin: beneficium ; ⇨ ↑ benefice ]
having a good effect OPP detrimental :
a drug that has a beneficial effect on the immune system
beneficial to/for
Cycling is highly beneficial to health and the environment.
an arrangement that is mutually beneficial (=it has advantages for everyone who is involved)
—beneficially adverb