Noun
じしょけい
食べたの辞書形は食べるです。
The dictionary form of ate is eat.
辞書形は分かるんですが、活用形がよく分かりません。
I'm fine with dictionary form, but I have trouble with conjugated form.
この言葉の辞書形を書きなさい。
Write the dictionary form of this word.
This is a combination of the word 辞書 "dictionary" and the suffix 〜形 or "form." Put them together and you get dictionary form!
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.