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Des Moines [Des Moines 词源字典]: city in Iowa, U.S., named for French Rivière des Moines, the river that flows past it, which traditionally is derived from French des moines "of the monks," in reference to missionaries, but this probably is a fur trappers' folk-etymologizing of a name of the native people who lived there.

The place appears in a 1673 text as Moinguena, and historians believe this represents Miami-Illinois mooyiinkweena, literally "shitface," from mooy "excrement" + iinkwee "face;" a name given by the Peoria Indians (whose name has itself become a sort of insult) to their western neighbors. It is not unusual for Indian peoples to have hostile or derogatory names for others, but this seems an extreme case.[Des Moines etymology, Des Moines origin, 英语词源]
distinguish (v.): 1560s, from Middle French distinguiss-, stem of distinguer, or directly from Latin distinguere "to separate between, keep separate, mark off, distinguish," perhaps literally "separate by pricking," from dis- "apart" (see dis-) + -stinguere "to prick" (compare extinguish and Latin instinguere "to incite, impel").

Watkins says "semantic transmission obscure;" the sense might be from "pricking out" as the old way to make punctuation in parchment or some literal image, but de Vaan derives the second element from a different PIE root meaning "to push, thrust."
The meanings of ex- and restinguere 'to extinguish' and distinguere seem quite distinct, but can be understood if the root meant 'to press' or 'push': ex-stinguere 'to put a fire out', re-stinguere 'to push back, suppress', and dis-stinguere 'to push apart [thence] distinguish, mark off ...."
The suffix -ish is due to the influence of many verbs in which it is the equivalent of Old French -iss-, ultimately from Latin inchoative suffix -iscere (this is also the case in extinguish, admonish, and astonish). Related: Distinguishing. The earlier form of the verb was distinguen (mid-14c.).
inguinal (adj.): 1680s, from Latin inguinalis "of the groin," from inguen (genitive inguinis) "groin," from PIE *engw- "groin, internal organ" (cognates: Greek aden "gland").