SIL

SIL as an acronym may refer to:
* Safety Integrity Level, as defined by IEC 61508.
* Son-in-law or sister-in-law, an on-line and text messaging usage
* Software-in-the-Loop ('SIL' or 'SiL' or 'SWIL'), a method used in (software) regression testing
* Squamous intraepithelial lesion, abnormal tissue situated within a squamous epithelium, often associated with pre-cancerous and cancerous growths in any of several organ-specific epithelia
* South Island Line, a plan of MTR Hong Kong
* Societas Internationalis Limnologiae also known as International Society of Limnology

SIL may also refer to:
* SIL International, a global Christian non-profit organization that studies lesser-known languages
* SIL code, a three-letter language code developed by SIL International.
* SIL : Solid Immersion Lens

Sil may refer to:
* Sil (Doctor Who), a villain from the British science-fiction series "Doctor Who"
* the named female character member of the Species (alien species) appearing in the science fiction film "Species"
* Sil (Urban Dance Squad), a member of the Dutch rap-metal band "Urban Dance Squad"
* Sil River, a river in Galicia, Spain
* Sil (Xerox Star), a vector drawing program for the Xerox Star computer system
* Sill, a part of a window frame, uncommonly spelled 'sil'
* Narasingha Sil, historian