none
Not any; not one of a group or amount.
The word none means not any, or not one. When you check your backpack for pencils and find none, you have zero pencils. When a teacher asks who forgot their homework and none of the students raise their hands, not a single person forgot.
None can feel a bit formal or old-fashioned compared to just saying “no” or “zero,” but it's useful when you want to be emphatic or clear. If someone asks whether any cookies remain in the jar, you might answer “none” to make it absolutely clear: there aren't any left.
The word works with both singular and plural meanings. You might say “none of the students were absent” (thinking of the group) or “none of the cake was left” (thinking of a single thing). Either way works fine.
People sometimes confuse none with “nun” (a woman who lives in a religious community), but they're completely different words. None always means an absence or lack of something: none of the lights were on, none of the answers seemed right, none of the players scored.