English abbreviations from shy to siad
- SHY (Sexual Health Youth)
- SI (Slovenia (ISO 3166 and FIPS 10-4 country code digram))
- si — (s) Sinhalese language (ISO 639 (1 code))
- SI/TA (Shut In/Temporarily Abandoned)
- SIA (Xiguan Airport)
- SIAA (Societas Iuridica Antiliana et Arubana)
- SIAC (School Improvement Accountability Committee)
- SIAD (Sierra Army Depot)