- (abbreviation) . emergency room.
- (abbreviation) . Elizabeth Regina.
- (abbreviation) . (computing) entity-relationship model or entity-relationship diagram.
- (abbreviation) . (biology) endoplasmic reticulum.
- (abbreviation) . (baseball) The statistic "Earned Run"; a run that was scored without the aid of an error by the fielding team that is charged to the pitcher responsible for allowing the runner that scored to reach base.
- Interjection. (UK) (non-gloss definition, Said when hesitating in speech.) .
- Verb. (informal) To utter the word "er" when hesitating in speech, found almost exclusively in the phrase '''um and er'''.