Rōmaji
ABC no A no ji mo nai
Type
idiom
Literal Meaning
one doesn’t even have the character A in ABC.
Meaning
not have/show the slightest element/sign of ABC; not know the first things about ABC
Synonym
かけらもない
Additional Info
“ABC” and “A” denote an arbitrary noun or adjective and its initial character, respectively. This is rather a colloquial expression, but when you use it in writing and the initial letter of ABC is kanji, the first hiragana of its reading is often used (see the 2nd example sentence). Note that it usually contains a sarcastic or disapproving tone.
Due to its flexible form, this is probably one of the trickiest Japanese expressions to document in a dictionary (and hence it’s rarely covered). Another example of such an expression is NOUN NOUN した.
Example
彼にはオシャレのオの字もない
He doesn’t know the first thing about fashion.
彼の仕事を手伝ってあげたのに、感謝のかの字もなかった。
I helped him with his work but he didn’t show the slightest sign of gratitude.