Signor

google

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Italian, from Latin senior (see senior).

wiktionary

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Borrowed from Italian signor, apocopic form of signore. Doublet of senior.

etymonline

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signor (n.)

an Italian lord or gentleman, 1570s, from Italian signore, from Latin seniorem, accusative of senior "older" (from PIE root *sen- "old"). Feminine form signora is from 1630s; diminutive signorina is first recorded 1820.