To my surprise, he didn't know how to use the dictionary.とは 意味・読み方・使い方

He had no [little] idea what these words meant.

I probably did not go as far as looking that word up in the dictionary.

I'm never certain about the use of this word.

learning from dictionaries

I may have said something to that effect, but I can not have used such words.

That word is not (given) in my dictionary.

It is indescribable no matter what words are used.

I have never used this word.

No one uses that word anymore since it is old.

I can't remember the meaning of the word that I looked up yesterday.

I don't know how to operate a spinning wheel.

If you don't know the meaning of the word, you have to look it up in the dictionary.

It is important to guess the meaning of unknown words from the context.

Tatoeba is the website I use when I don't find enough examples in dictionaries.

The word is not in my dictionary.

That word isn't in my dictionary.

This word is not given [listed] in my dictionary.

I don't know where this expression comes from.

I can't remember the meaning of the word that I looked up yesterday.

a thing or a person who is unimportant

My dictionary doesn't have the word "impossible".

He does not know algebra and geometry well, still less calculus―not to speak of calculus.

Words failed me at the last minute.

It does not convey the exact meaning of the original word.

I underlined all the words I didn't know.

Hastily acquired knowledge was not enough to solve the problem.

The origin of this word is unknown.

I think the translation of that word is unsuitable.

From now on, I will not use that word.

He does not know how to treat [handle] his men.