Descriptive of an endogenous or semi-synthetically produced oligoribonucleotide complementary to mRNA and capable of base-pairing and annealing with mRNA to prevent translation; or of an oligodeoxyribonucleotide capable of binding to the major groove of polypurine-polypyrimidine sequences of DNA by Hoogsteen base pairing to silence a gene. Also used to describe one of the two strands of double-stranded DNA, usually that which has the same sequence as the mRNA, i.e. the non-transcribed strand. However, there is not universal agreement on this convention, and a preferred designation is coding strand for the strand whose sequence matches that of the mRNA, and non-coding strand for the complementary strand (i.e. the transcription template, or transcribed strand).