Non-coding RNA (ncRNA) refers to a variety of RNA molecules that are not translated into proteins. In the past, such RNAs were also called small ribonucleic acids (sRNAs). However, some ncRNA molecules are actually quite large. Other lesser used synonyms are non-messenger RNA (nmRNA), small non-messenger RNA (snmRNA), or functional RNA (fRNA).
  The part of the DNA sequence that is transcribed exclusively into non-coding RNA is called an RNA gene or a non-coding RNA gene. Non-coding RNA genes are used to produce tRNA (transfer RNA) and rRNA (ribosomal RNA), as well as some small RNAs such as snoRNAs, microRNAs, siRNAs and piRNAs; the larger ones are Xist, Evf, Air, CTN and #80C680.