たりとも means "not even one": not the smallest possible amount is allowed or there. It follows plus the counter you'd normally use for what is counted – , , , – and the sentence ends in a negative.
。
I don't want to waste a single second.
。
Don't let a single one of them get away.
。
I won't lend you one yen.
、。
You must not breathe a word about this.
The negative can be a plain ない, a ず, a ban like きごう〜 or きごう〜, or . Without it the sentence falls apart: ×一秒たりとも大切だ.
たりとも or も
きごう〜 says the same thing in everyday Japanese. たりとも is formal and written, and it sounds resolute or severe: orders, vows, rules. In ordinary conversation, も is the choice; たりとも in a casual chat sounds theatrical.
。
I don't have a single yen.
。
Don't waste a single yen.
たりとも, すら and さえ
and
also mean "not even", and they go on any noun:
. たりとも only goes on 一 and a counter, the smallest unit there is.
。
I don't even know his name.
。
You mustn't let your guard down for an instant.
Usage notes
These go beyond 一 plus a counter.
Never once
With or and きごう〜, たりとも says something has never happened, not once.
。
There hasn't been a single day when I forgot her.
何人たりとも
means "nobody at all, whoever they are". It belongs to notices and stiff formal speech.
、。
No one, whoever they are, may enter here.
Lingaku