noun /sí/
Definitions
  1. The name of the Latin script letter S/s.
Other entries with this spelling
Wiktionary records 4 entries spelled “sí”. You're reading one of them; here are the others.
Possibly used in
Source: Wiktionary · etymology 1, where this word is spelled “si”. Reference: en-si-yo-noun-IyX2HhRs