justly (adv.)

early 14c., "in an adjacent position, closely" (obsolete except in dialect), from just (adj.) + -ly (2). Meanings "truthfully, honestly" and "equitably, with justice, fairly" are from late 14c. Sense of "justifiably, with good reason, accurately" is from c. 1400; that of "legally, legitimately, rightfully" is early 15c.