USEFULLY
usefully
(adverb) in a useful manner; “extra money could be usefully spent on this project”
Source: WordNet® 3.1
Etymology
Adverb
usefully (comparative more usefully, superlative most usefully)
In a useful manner; in a way that achieves something
Source: Wiktionary
Use"ful*ly, adv.
Definition: In a useful manner.
USEFUL
Use"ful, a.
Definition: 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.
To what can I useful! Milton.
Source: Webster’s Unabridged Dictionary 1913 Edition