SI adjective 1noun 15forms 1 adjective1 •Initialism of sacroiliac. noun15 •(UK, Australia) Initialism of statutory instrument. •Initialism of self-injury. •Initialism of suicidal ideation. •Initialism of signal integrity. •Initialism of systems integration. •Initialism of spark ignition. •Initialism of subinspector (of police, etc).India's first transgender SI •Initialism of supporting information. •(slang) Initialism of self-insertion (of the author into fan fiction). •Initialism of swarm intelligence. •Initialism of special intelligence. •(Philippines) Initialism of sales invoice. •Initialism of surface interval. •Initialism of synthetic intelligence. •Initialism of systematic internaliser. formsSIs