1) The small RNA molecules, 73-80 nucleotides long, that function during translation to align amino acids at the ribosomes in a sequence determined by the mRNA. There are about 30 different transfer RNAs. Each recognizes a specific codon set on the mRNA through its own anticodon, and as aminoacyl tRNAs, each carries a specific amino acid to the ribosome to add to the elongating peptide chains.

2) A class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of mRNA. The role of tRNAs in protein synthesis is to bond with amino acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code carried by mRNA.

3) A relatively small RNA that transfers a particular amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation -- called also adapter RNA, soluble RNA, tRNA.

4) Transfer RNA (tRNA) is a small RNA molecule that participates in protein synthesis. Each tRNA molecule has two important areas: a trinucleotide region called the anticodon and a region for attaching a specific amino acid. During translation, each time an amino acid is added to the growing chain, a tRNA molecule forms base pairs with its complementary sequence on the messenger RNA (mRNA) molecule, ensuring that the appropriate amino acid is inserted into the protein.