From Middle English well knowen.

• (America) IPA: /ˌwɛlˈnoʊn/
• (RP) IPA: /ˌwɛlˈnəʊn/

well-known (comparative better-known, superlative best-known)

1. Familiar, famous, renowned or widely known.

   Antonyms: little-known

   • 1918, W[illiam] B[abington] Maxwell, chapter XV, in The Mirror and the Lamp, Indianapolis, Ind.: The Bobbs-Merrill Company, →OCLC ↗:

     Edward Churchill still attended to his work in a hopeless mechanical manner like a sleep-walker who walks safely on a well-known round. But his Roman collar galled him, his cossack stifled him, his biretta was as uncomfortable as a merry-andrew's cap and bells.

2. (computing, not comparable) Generally recognized; reserved for some usual purpose.
   • 1972, Vint Cerf, Jon Postel, RFC 322 - Well known socket numbers:

     We would like to catalog other sockets which are supposed to be well-known

   • 2003, John Mueller, .NET development security solutions:

     If the call to this function fails, you can assume the SID was invalid — even if it's a well-known SID.

   • 2007, Larry L Peterson, Bruce S Davie, Computer networks: a systems approach:

     A common approach is for the server to accept messages at a well-known port.

• French: bien connu
• German: wohlbekannt, wohl bekannt, berühmt
• Italian: famoso, rinomato, noto, celebre, popolare
• Russian: знамени́тый
• Spanish: consabido, de marras, famoso