~ 1 [ 'ɛksən ]
■ noun Biochemistry a segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence. Compare with intron .
Origin
1970s: from expressed (see express 1 ) + -on .
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~ 2 [ 'ɛksɒn ]
■ noun Brit. each of the four officers acting as commanders of the Yeomen of the Guard.
Origin
C18: representing the pronunciation of Fr. exempt 'free from' (because they were exempt from normal duties).