Synonyms for Useful (same or very similar meaning)
WordNet sense 1 (having utility often to the exclusion of values):
utilitarian
WordNet sense 2 (capable of being put to good use):
serviceable
WordNet sense 3 (of service or assistance):
helpful
WordNet sense 4 (being of use or service):
utile
WordNet sense 5 (designed for or capable of a particular function or use):
functional
From the ODE community, based on WordNet
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