| 1. | to free from an obligation or liability to which others are subject; release: to exempt a student from an examination. |
| 2. | released from, or not subject to, an obligation, liability, etc.: organizations exempt from taxes. |
| 3. | a person who is exempt from an obligation, duty, etc. |
| 4. | (in Britain) exon. |

| (in Britain) one of four yeomen of the guard who act as commanding officers in the absence of higher authority. |

Stretches of DNA in genes that code for proteins. In eukaryotes, exons in a given gene are generally separated from each other by stretches of DNA that do not contain instructions for constructing proteins. (Compare intron.)
exon ex·on (ěk'sŏn)
n.
A nucleotide sequence in DNA that carries the code for the final mRNA molecule and thus defines a protein's amino acid sequence. Also called coding sequence.