Origin and history of mesmeric

"the doctrine that one person can exercise influence over the will and nervous system of another and produce certain phenomena by virtue of a supposed emanation called animal magnetism," 1798, from French mesmérisme, named for Franz Anton Mesmer (1734-1815), Austrian physician who developed a theory of animal magnetism and a mysterious body fluid which allows one person to hypnotize another and propounded it in 1778 in Paris. The word, if still used is practically synonymous with hypnotism or artificial somnambulism. Another similar word for the same effect was braidism. An old term for "hypnotic suggestion" was mesmeric promise. Related: Mesmerist

Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).

In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.