I heed the etymological fallacy, but how can I connect the etymology to cases' meanings or rationalise/make sense of these esoteric words? I'm always confused as to which is which, and I need to consult a dictionary every time. Supplementary info:
ablative. Etymonline: mid-15c., from Middle French ablatif, from Latin (casus) ablativus "(case) of removal," expressing direction from a place or time, coined by Julius Caesar from ablatus "taken away," past participle of auferre "carrying away," from ab- "away" + irregular verb ferre (past participle latum see oblate); "to carry, to bear". The Latin case of adverbial relation, typically expressing the notion "away from," or the source or place of an action.
accusative. Etymonline: grammatical case whose primary function is to express destination or goal of motion, mid-15c., from Anglo-French accusatif, Old French acusatif, or directly from Latin (casus) accusativus "(case) of accusing," from accusatus, past participle of accusare (see accuse).
1. How does it make sense to accuse a noun, a pronoun or an adjective?
dative. Etymonline: mid-15c., from Latin dativus "pertaining to giving," from datus "given" (see date (n.1)); in grammatical use from Greek dotike (ptosis) "dative (case)," from dotikos "of giving nature," from dotos "given," from PIE root *do- "to give," from the same PIE root as the Latin word. In law, "that may be disposed of at pleasure," from 1530s. Typically the case of the indirect object, but sometimes also denoting "motion toward." In old Germanic languages, the "fourth case," catch-all for Indo-European dative, ablative, locative, and other cases.
genitive. Etymonline late 14c., from Old French genitif or directly from Latin (casus) genitivus "case expressing possession, source, origin," from genitus (past participle of gignere; see genital); misused by Latin grammarians to render Greek genike (ptosis) "generic (case)," expressing race or kind (see genus). The noun meaning "the genitive case in grammar" is from 1610s.
nominative. Etymonline: 1540s, "to call by name," back-formation from nomination or else from Latin nominatus, past participle of nominare "to name, call by name, give a name to," also "name for office,"" from nomen "name" (see name (n.)). Later "to appoint to some office or duty" (1560s); "to formally enter (someone) as a candidate for election" (c.1600). It also occasionally was used from c.1600 with a sense "give a name to." Related: Nominated; nominating.
2. What's being named?
vocative. early 15c., "showing the person or thing spoken to," from Middle French vocatif, from Latin vocativus (casus) "(case of) calling," from vocatus, past participle of vocare "to call" (see voice (n.)). The Latin is a translation of Greek kletike ptosis, from kletikos "related to calling," from kletos "called." As a noun from 1520s.
3. How does call apply here? Speaking to a person or thing differs from calling him or it?
Footnote: I omit the locative and instrumental cases; the modifiers (italicised) are self-explanatory.