advantageous, profitable; of beneficial efficiency ...c1420 obs. rare
from avail (vb. to be effectual, serviceable, or of use) + -ant
FIRST DOCUMENTED USE
c1420 - see EXAMPLE below
"...Thaire kyndes beth, oon is peche Armenye,
Precox is next, the thridde is duracyne.
But if this tree to sore in sonne drie
Hepe erthe aboute and humoure vespertyne,
Eke thing object the fervoure of declyne.
A serpent skynne doon on this tree men lete
Avaylant be to save it in greet hete..."
(Their sorts are the Armenian, the Precox, and the cling-stone.
If the tree be too sorely sun-dried, heap earth about it.
Let anything placed as a protection ward off the heat.
Men think a serpent's skin avails to save it.)
From: Palladius On Husbondrie, Part 1
- Rutilius Taurus Aemilianus Palladius