From avail + -ful.
availful (comparative more availful, superlative most availful)
- (obsolete) Profitable, useful; of much avail.
- 1603, John Florio, translating Michel de Montaigne, Essays, II.10:
- These Logicall and Aristotelian ordinances are not availfull [transl. à propos] for me, who onely endevour to become more wise and sufficient, and not more wittie or eloquent.