assert (v.)youdaoicibaDictYouDict
c. 1600, "declare," from Latin assertus, past participle of asserere "claim, maintain, affirm" (see assertion). Related: Asserted; asserting. To assert oneself "stand up for one's rights" is recorded from 1879.
silent (adj.)youdaoicibaDictYouDict
c. 1500, "without speech, silent, not speaking," from Latin silentem (nominative silens) "still, calm, quiet," present participle of silere "be quiet or still" (see silence (n.)). Meaning "free from noise or sound" is from 1580s.

Of letters, c. 1600; of films, 1914. In the looser sense "of few words," from 1840. Phrase strong, silent (type) is attested from 1905. Silent majority in the political sense of "mass of people whose moderate views are not publicly expressed and thus overlooked" is first attested 1955 in a British context and was used by John F. Kennedy but is most associated in U.S. with the rhetoric of the Nixon administration (1969-74).
It is time for America's silent majority to stand up for its rights, and let us remember the American majority includes every minority. America's silent majority is bewildered by irrational protest. [Spiro T. Agnew, May 9, 1969]
In Victorian use, the phrase meant "the dead" (1874; compare Roman use of the noun plural of "silent" to mean "the dead"). Silence is golden (1831) is Carlyle's translation ["Sartor Resartus"] of part of the "Swiss Inscription" Sprechen ist silbern, Schweigen ist golden. In one 14c. text Latin "one who is silent" is translated by a beere stille.
stand-up (adj.)youdaoicibaDictYouDict
1811, "courageous," originally of fist fights, denoting a manful contest without fake falls, from the verbal phrase (early 12c. in sense "rise to one's feet"), from stand (v.) + up (adv.). To stand up "hold oneself against an opponent" is from c. 1600; as stand up to in the same sense from 1620s. To stand up for "defend the cause of" is from c. 1600. To stand (someone) up "fail to keep an appointment" is attested from 1902. Stand-up comic first attested 1966. Catch-phrase will the real _______ please stand up? is from the popular CBS game show "To Tell the Truth," which debuted in 1956.