1. Abjure and adjure
Abjure, from Latin by way of French, means “to deny” or “to renounce,” or “to avoid.” Adjure, which took the same route to English, means “to confirm” or “to command,” or “to advise or urge.” In some senses, therefore, they are near antonyms. (That’s logical: Ab- means “from” and ad- means “to.”) However, they do share a root syllable, the same one that is the basis of jury, jurisprudence, just, justice, and other terms from the realm of law.
2. Chafe and chaff
Chafe, ultimately derived from the Latin term calefacere, “to make warm or hot,” originally meant just that, but then, from the added sense of “rubbing to make warm,” it acquired the negative connotations of “make sore by rubbing” and then, by association, “irritate.” Chaff, an unrelated word, comes from Old English and refers to seed husks and, by extension, anything discarded as worthless. By association with the cloud of husks and other debris produced during threshing of grain, a burst of tiny scraps of metal ejected from aircraft to interfere with enemy radar is called chaff.