1. [v]  provide interlinear explanations for words or phrases; "He annotated on what his teacher had written"
2. [v]  add explanatory notes to or supply with critical comments"The scholar annotated the early edition of a famous novel"

1. \An"no*tate\, v. t. [imp. & p. p. {Annotated}; p. pr. &
   vb. n. {Annotating}.] [L. annotatus; p. p. of annotare to
   annotate; ad + notare to mark, nota mark. See {Note}, n.]
   To explain or criticize by notes; as, to annotate the works
   of Bacon.
   

2. \An"no*tate\, v. i.
   To make notes or comments; -- with on or upon.
   

annotation