诂 詁 gu3
to comment; to explain

strokes 7
radical
讠
言
strokes after radical 5
训诂 訓詁 xun4 gu3
to interpret and make glossaries and commentaries on classic texts

训诂学 訓詁學 xun4 gu3 xue2
study of classic texts, including interpretation, glossaries and commentaries