Squarely comes from square + -ly; square comes from Old French esquarre, from Vulgar Latin *exquadra, from Latin ex- + quadra ('a square'), from quattuor ('four'). The historical chain includes Old French esquarre, Latin quadra, and Latin quattuor. The quoted older senses, "a square" and "four", supply the semantic anchors for squarely. The formation is best read as suffixal, compound, and borrowed: the word squarely carries its older form-history into a compact English lexical shape. In present English it is used as a adv, "directly and exactly; in a straightforward manner". Related English forms include square. The result is a adv whose etymology preserves both the older form and the later English specialization.