Really small amount

IOTA

Think of the ninth letter in the Greek alphabet, often used to describe something almost too tiny to measure.

The clue "Really small amount" points to "IOTA" because an iota is a tiny, almost insignificant quantity—so small it’s often used to mean "the least bit." The word comes from the Greek alphabet (where it’s the ninth letter) but in English, it’s mostly used figuratively, like in "not one iota of truth." No wordplay here, just a straightforward definition.