selfsame

What it means

1. not comparableChiefly preceded by the: precisely the same; the very same; the same not only in being similar but in being identical.

   For both of you are Birds of ſelfe-ſame Feather.

   c. 1591–1592 (date written), William Shakespeare, “The Third Part of Henry the Sixt, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act III, scene iii], page 162, column 1

   5 more examples

   In my ſchoole dayes, vvhen I had loſt one ſhaft [i.e., arrow], / I ſhot his fellovv of the ſelfe-ſame flight / The ſelfe-ſame vvay, vvith more aduiſed vvatch / To finde the other foorth, and by aduentring both, / I oft found both. I vrge this child-hoode proofe, / Becauſe vvhat follovves, is pure innocence.

   c. 1596–1598 (date written), W[illiam] Shakespeare, The Excellent History of the Merchant of Venice. […] (First Quarto), [London]: […] J[ames] Roberts [for Thomas Heyes], published 1600, →OCLC, [Act I, scene i]

   He and his Horse, were of a piece. / One Spirit did inform them both, / The self-same Vigor, Fury, Wroth: […]

   1662 (indicated as 1663), [Samuel Butler], “[The First Part of Hudibras]. Canto II.”, in Hudibras. The First and Second Parts. […], London: […] John Martyn and Henry Herringman, […], published 1678, →OCLC; republished in A[lfred] R[ayney] Waller, editor, Hudibras: Written in the Time of the Late Wars, Cambridge, Cambridgeshire: University Press, 1905, →OCLC, page 40

   He trod the very ſelf-ſame ground you tread, / And victory refuted all he ſaid.

   1781 (date written), William Cowper, “Table Talk”, in Poems, London: […] J[oseph] Johnson, […], published 1782, →OCLC, page 21

   Mine be the strength of spirit fierce and free, / Like some broad river rushing down alone, / With the selfsame impulse wherewith he was thrown / From his loud fount upon the echoing lea:— […]

   1832 December (indicated as 1833), Alfred Tennyson, “Sonnet”, in Poems, London: Edward Moxon, […], →OCLC, page 1

   And Quack and Dupe, as we must ever keep in mind, are upper-side and under of the self-same substance; convertible personages: turn up your dupe into the proper fostering element, and he himself can become a quack; […]

   1843 April, Thomas Carlyle, “Morrison’s Pill”, in Past and Present, American edition, Boston, Mass.: Charles C[offin] Little and James Brown, published 1843, →OCLC, book I (Proem), page 26

   Synonyms: identical, indifferent, nondifferent, one and the same, self, undifferent, undifferentiated · Antonyms: other, different, differing, dissimilar, diverse, other, unalike, unlike

In a sentence

For both of you are Birds of ſelfe-ſame Feather.

c. 1591–1592 (date written), William Shakespeare, “The Third Part of Henry the Sixt, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act III, scene iii], page 162, column 1

Where it comes from

1. Proto-Indo-European*sem-“one, together”
2. Old Norsesamr“same; agreeing, of one mind”
3. Proto-Indo-European*swé“self”
4. Old Englishself
5. Middle Englishself sam
6. Englishselfsame

PIE word *swé From Middle English self sam, self same, selve same (“the very same, selfsame”) [and other forms], from self (“that specific (person mentioned), herself, himself, itself, themselves”, pronoun) (from Old English self, ultimately from Proto-Indo-European *swé (“self”)) + sam, same (“(adjective) equal, identical; unchanging; referred to earlier, abovenamed, aforementioned; (adverb) again, repeatedly”) (from Old Norse samr (“same; agreeing, of one mind”), ultimately probably from Proto-Indo-European *sem- (“one, together”)). The English word is analysable as self + same. Cognates * Danish selvsamme (“identical, selfsame”) * Old High German selbsama (“identical, selfsame”)