adjuration (n.)

word-forming element expressing direction toward or in addition to, from Latin ad "to, toward" in space or time; "with regard to, in relation to," as a prefix, sometimes merely emphatic, from PIE root *ad- "to, near, at."

Simplified to a- before sc-, sp- and st-; modified to ac- before many consonants and then re-spelled af-, ag-, al-, etc., in conformity with the following consonant (as in affection, aggression). Also compare ap- (1).

In Old French, reduced to a- in all cases (an evolution already underway in Merovingian Latin), but written forms in French were refashioned after Latin in 14c. and English did likewise 15c. in words it had picked up from Old French. In many cases pronunciation followed the shift. Over-correction at the end of the Middle Ages in French and then English "restored" the -d- or a doubled consonant to some words that never had it (accursed, afford). The process went further in England than in France, where the vernacular sometimes resisted the pedantic, resulting in English adjourn, advance, address, advertisement (Modern French ajourner, avancer, adresser, avertissement). In modern word-formation sometimes ad- and ab- are regarded as opposites, but this was not in classical Latin.

mid-15c., "one who practices law;" 1620s, "a legal writer, one who professes the science of the law," from French juriste (14c.), from Medieval Latin iurista "jurist," from Latin ius (genitive iuris) "a right," especially "legal right or authority, law," also "place where justice is administered, court of justice," from Old Latin ious, perhaps literally "sacred formula," a word peculiar to Latin (not general Italic) that originated in the religious cults, from PIE root *yewes- "law" (compare Latin iurare "to pronounce a ritual formula," Vedic yos "health," Avestan yaoz-da- "make ritually pure," Irish huisse "just"). Related: Juristic. The more mundane Latin law-word lex meant specific laws as opposed to the body of laws.

The Germanic root represented by Old English æ "custom, law," Old High German ewa, German Ehe "marriage," sometimes is associated with this group, or it is traced to PIE *ei- "to go."

late 14c., coniuracioun, "conspiracy, a plot, act of plotting" (senses now obsolete), also "a calling upon something supernatural, act of invoking by a sacred name, invocation of spirits, magic spell or charm," from Old French conjuracion "spell, incantation, formula used in exorcism" and directly from Latin coniurationem (nominative coniuratio) "a swearing together, conspiracy," in Medieval Latin "enchantment," noun of action from past-participle stem of coniurare "to swear together; conspire," from assimilated form of com "with, together" (see con-) + iurare "to swear," from ius (genitive iuris) "law, an oath" (see jurist).