Definitions from Wiktionary (Si)

▸ noun:  International System of Units
▸ noun:  (music) A syllable used in solfège to represent the seventh note of a major scale.
▸ noun:  A diminutive of the male given name Simon.
▸ noun:  A diminutive of the male given name Silas.
▸ noun:  A river in Shandong, China.
▸ noun:  A county of Suzhou, Anhui, China.
▸ noun:  (historical) Various prefectures of imperial China.
▸ noun:  Initialism of Smithsonian Institution.
▸ noun:  (electronics) Initialism of signal integrity.
▸ noun:  (technology) Initialism of systems integration.
▸ noun:  Initialism of self-injury. [self-harm]
▸ noun:  Initialism of suicidal ideation. [Feelings, thoughts, contemplation of, a preoccupation with or a general desire for one's own suicide, or the idea of ceasing to exist.]
▸ noun:  (fandom slang) Initialism of self-insertion. (of the author into fan fiction) [(narratology) A literary device in which the author writes himself or herself into the story as a character.]
▸ noun:  (mechanical engineering) Initialism of spark ignition.
▸ noun:  Initialism of supporting information.
▸ noun:  Initialism of special intelligence.
▸ noun:  (finance) Initialism of systematic internaliser.
▸ noun:  Initialism of swarm intelligence. [(artificial intelligence) The collective behavior of decentralized, self-organized systems, whether natural or artificial.]
▸ noun:  Initialism of synthetic intelligence. [Synonym of artificial intelligence]
▸ noun:  (Philippines, accounting, business) Initialism of sales invoice.
▸ noun:  (UK, Canada, Australia, law) Initialism of statutory instrument. [(UK, Ireland, Canada, Australia, law) In some common law jurisdictions, a form of delegated legislation enacted under a power derived from an act of parliament.]
▸ noun:  Initialism of subinspector (of police, etc) [A subordinate inspector.]
▸ noun:  (underwater diving) Initialism of surface interval. [(underwater diving) time spent outside the water (i.e. on the surface) between underwater dives. This time is considered when calculating decompression requirements for the subsequent dive]
▸ adjective:  (anatomy, medicine) Initialism of sacroiliac. [(anatomy) Relating to the sacrum and ilium, or to the region of the lower back where they are located.]
▸ noun:  Alternative form of Xi [A river in China, the western tributary of the Pearl.]

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