A cis-acting sequence that increases the utilization of (some) eukaryotic promoters, and can function in either orientation and in any location (upstream or downstream) relative to the promoter.
Comment:
An enhancer may participate in an enhanceosome GO:0034206. A protein-DNA complex formed by the association of a distinct set of general and specific transcription factors with a region of enhancer DNA. The cooperative assembly of an enhanceosome confers specificity of transcriptional regulation. This comment is a place holder should we start to make cross products with GO.