ADV. almost His response was almost instant.
1 short period of time
ADJ. brief, fleeting For a brief instant, I thought she was going to fall. | one, single His news was too important to be contained for a single instant longer.
VERB + INSTANT pause for He paused for an instant before continuing.
PREP. for an ~ Just for an instant I thought he was going to refuse. | in an ~ It was all over in an instant. | ~ after/before She woke up in the instant before the phone rang.
2 single point in time
ADJ. (any) given, (any) one At any given instant the distribution of molecular speeds is always constant under the same conditions. | very He took out his keys to lock the door. At that very instant the door flew open and a man ran into the room.
PREP. at … ~ The bomb could go off at any instant.