'Useful' definitions:

Definition of 'useful'

From: WordNet
adjective
Being of use or service; "the girl felt motherly and useful"; "a useful job"; "a useful member of society" [syn: useful, utile] [ant: useless]
adjective
Having a useful function; "utilitarian steel tables" [syn: utilitarian, useful]

Definition of 'Useful'

From: GCIDE
  • Useful \Use"ful\, a. Full of use, advantage, or profit; producing, or having power to produce, good; serviceable for any end or object; helpful toward advancing any purpose; beneficial; profitable; advantageous; as, vessels and instruments useful in a family; books useful for improvement; useful knowledge; useful arts. [1913 Webster]
  • To what can I useful! --Milton. [1913 Webster]