ˈyüsfəl adjective
Etymology: use (I) + -ful
: capable of being put to use : having utility : advantageous
the Communists find him just as useful as an opponent — Time
especially : producing or having the power to produce good : serviceable for a beneficial end or object
all sorts of useful implements such as axes, chisels, gouges, arrowheads — American Guide Series: Rhode Island
useful to remind ourselves occasionally of our limitations
no useful rain had fallen for five or six months — Sydney (Australia) Bulletin