headnote; marginal note; annotation at the top of a page
Refers to a note or comment placed at the top of a page or in the margin, often in scholarly or literary works.
この本の頭注には、難しい言葉の説明が書いてある。
The headnotes in this book explain difficult words.
古
Classical Japanese textbooks often have marginal notes.
注釈 is a general term for annotation or commentary, not specifying position; 頭注 specifically refers to notes at the top.
Standard modern spelling for 'headnote' or 'marginal note'.
Variant using the older 註 character for 'annotation'; less common in modern texts.
Compound of 頭 (head, top) and 注 (annotation, note). The spelling 頭註 uses the older form 註 for 'note'.