イタリア語のin-, not, not, -cogn, to know, to know, 語源的にはknow, cognizanceと同じ。
英語の語源
incognito (adj./adv.)
1640s, from Italian incognito "unknown," especially in connection with traveling, from Latin incognitus "unknown," from in- "not, opposite of, without" (see in- (1)) + cognitus, past participle of cognoscere "to get to know" (see cognizance). Fem. form incognita was maintained through 19c. by those scrupulous about Latin. Incog was a common 18c. colloquial abbreviation.
例文
1. Hotel inspectors have to travel incognito .
ホテルの検査員が巡回するときは正体を隠す必要があります。
2.He preferred to remain incognito .
彼は名前を隠し続けるのが好きだ。
3.Movie stars often prefer to travel incognito .
映画スター旅行はしばしば身分を隠すのが好きだ。
4.The prince travelled incognito to avoid crowds and ceremonies.
王子は人ごみを避け、歓迎行事を避けるためにミニチュア旅行をした。
5.I dismissed my old man here，and stayed incognito for three or four days.