Antinode
Definition
The point on a standing wave that swings with the biggest motion — halfway between two nodes.
Technical definition
A point of maximum displacement amplitude in a standing wave, where incident and reflected waves always interfere constructively. Antinodes lie midway between adjacent nodes, spaced λ/2 apart.
Example
The middle of a jump rope twirled at its fundamental frequency is an antinode — it sweeps the widest arc while your hands (the nodes) barely move.
Common confusion
Antinodes have maximum displacement but zero pressure variation in sound waves — the exact opposite of nodes. Mixing up which quantity is extreme where is the classic standing-wave error.