Definition of "plaine"

Or plaine and perfite way of teachyng children, to vnderstand, write, and speake, the Latin tong, but specially purposed for the priuate brynging vp of youth in Ientlemen and Noble mens houses, and commodious also for all such, as haue forgot the Latin tonge, and would, by themselues, without a Scholemaster, in short tyme, and with small paines, recouer a sufficient habilitie, to vnderstand, write, and speake Latin.

1570, Roger Ascham, The Scholemaster