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.
The headnotes in this book explain difficult words.
Classical Japanese textbooks often have marginal notes.
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'.