SIS
sister, sis
(noun) a female person who has the same parents as another person; “my sister married a musician”
Source: WordNet® 3.1
Noun
sis (plural sises or sisses)
(informal) Clipping of sister.
Synonyms
• (sister): sissy
Anagrams
• ISS, SSI
Proper noun
SIS
(British) Initialism of Secret Intelligence Service.
Initialism of Schengen Information System.
Synonyms
(Secret Intelligence Service)
• MI6, Six, 6
• Secret Intelligence Service
Noun
SIS (uncountable)
Initialism of second impact syndrome.
Initialism of snow immersion suffocation.
Anagrams
• ISS, SSI
Source: Wiktionary
Sis, n.
Definition: A colloquial abbreviation of Sister.
Sis, n.
Definition: Six. See Sise. [Obs.] Chaucer.
Source: Webster’s Unabridged Dictionary 1913 Edition