Supreme Exalted Ruler, president of Sigma Alpha Rho fraternity

South Eastern Railway

Smooth Endoplasmic Reticulum

Serpens, a constellation (standard astronomical abbreviation)

Bulgarian name of the town of Serres, Greece

serine, amino acid (biochemistry abbreviation)

Social-Economic Council of the Netherlands

SER-Jobs for Progress, an employment and community development program run by the American GI Forum

Cadena SER, a Spanish radio channel

SIP Express Router (SER), a configurable proxy or redirect server for Session Initiation Protocol (SIP)

Ser (unit), an obsolete unit of capacity in India

Sequence of Events Recorder, an electronic device which monitors external inputs and records the time and sequence of the changes.

The infinitive verb "to be" in the Spanish and Portuguese languages