A pentose sugar important as a component of ribonucleic acid WordNet 3.0 & Open English WordNet

Ribose is a carbohydrate with the formula C5H10O5; specifically, it is a pentose monosaccharide with linear form H−−4−H, which has all the hydroxyl groups on the same side in the Fischer projection. Wikipedia

Ribose is a simple sugar and carbohydrate with molecular formula C5H10O5 and the linear-form composition H−−4−H. The naturally-occurring form, d-ribose, is a component of the ribonucleotides from which RNA is built, and so this compound is necessary for coding, decoding, regulation and expression of genes. Wikipedia

A naturally occurring pentose sugar, which is a component of the nucleosides and nucleotides that constitute the nucleic acid biopolymer, RNA. It is also found in riboflavin. Wiktionary

Naturally occurring pentose sugar. Wiktionary (translation)