〜たりとも〜ない

Meaning

Cites the smallest quantity or unit and strongly denies that even that exists or is permitted. Followed by a negative form such as 「〜ない」.

Examples

試合中は一瞬たりとも気を抜いてはいけない。 During a match, you must not let your guard down even for a single moment.
水不足の現在、一滴たりとも水を無駄にすることはできない。 With the current water shortage, we cannot waste even a single drop of water.