letter-perfect adj.

c. 1200, "graphic symbol, alphabetic sign, written character conveying information about sound in speech," from Old French letre "character, letter; missive, note," in plural, "literature, writing, learning" (10c., Modern French lettre), from Latin littera (also litera) "letter of the alphabet," also "an epistle, writing, document; literature, great books; science, learning;" a word of uncertain origin.

According to Watkins, perhaps via Etruscan from Greek diphthera "tablet" (with change of d- to l- as in lachrymose), from a hypothetical root *deph- "to stamp." In this sense it replaced Old English bocstæf, literally "book staff" (compare German Buchstabe "letter, character," from Old High German buohstab, from Proto-Germanic *bok-staba-m).

Latin littera also meant "a writing, document, record," and in plural litteræ "a letter, epistle, missive communication in writing," a sense passed through French and attested in English letter since early 13c. (replacing Old English ærendgewrit "written message," literally "errand-writing"). The Latin plural also meant "literature, books," and figuratively "learning, liberal education, schooling" (see letters).

The custom of giving the school letter as an achievement award in sports, attested by 1908, is said to have originated with University of Chicago football coach Amos Alonzo Stagg. Earlier in reference to colleges it meant "university degree or honor that adds initials to a name" (1888). Expression to the letter "precisely" is from 1520s (earlier after the letter, mid-14c.). Letter-quality (adj.) "suitable for (business) letters" is from 1977. For letters patent (with French word order) see patent (n.).

early 15c. classical correction of Middle English parfit "flawless, ideal" (c. 1300), also "complete, full, finished, lacking in no way" (late 14c.), from Old French parfit "finished, completed, ready" (11c.), from Latin perfectus "completed, excellent, accomplished, exquisite," past participle of perficere "accomplish, finish, complete," from per "completely" (see per) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put").

Often used in English as an intensive (perfect stranger, etc.), from the notion of "complete." Grammatical sense, in reference to verb tense describing an action as completed, is from c. 1500. As a noun, late 14c. ("perfection"), from the adjective.

The difference between the Preterit and the Perfect is in English observed more strictly than in the other languages possessing corresponding tenses. The Preterit refers to some time in the past without telling anything about the connexion with the present moment, while the Perfect is a retrospective present, which connects a past occurrence with the present time, either as continued up to the present moment (inclusive time) or as having results or consequences bearing on the present moment. [Otto Jespersen, "Essentials of English Grammar," 1933]