methylate

/M EH1 TH AH0 L IH0 T/
noun
  1. 1

    The anion -O-CH3- derived from methanol by loss of a proton; any salt containing this anion

verb
  1. 1

    To add, or treat with methyl alcohol (see methylated spirits)

  2. 2

    To add a methyl group to a compound

  3. 3

    To add a methyl group to a nucleic acid as part of the process of gene expression

Source: https://en.wiktionary.org/wiki/methylate