ETYMOLOGY
from Greek πολυµαθής (having learnt much), from πολυ- (poly-, much) + μάθη (learning) from the base of µανθάνειν (to learn)
EXAMPLE (for n.)
“… To be counted writers, scriptores ut Salutentur, to be thought and held Polumathes and Polyhistors, apud imperitum vulgus ob ventosæ nomem artis, to get a paper-kingdom: nulla spe quæstus sed ampla famæ, in this precipitate, ambitious age, nunc ut est sæculum, inter immaturam eruditionem, ambitiosum et præceps (’tis Scaliger’s censure); and they that are scarce auditors, vix auditores, must be masters and teachers, before they be capable and fit hearers. …”
From: The Anatomy of Melancholy
By Robert Burton, 1624
Lexicophilia 