Nodes are stationary points where a vibrating mode has no motion

Evidence

A given pure mode, with only one stalk raised, will have a pattern of vibration involving most of the beads, except for the occasional bead that isn’t moving. Such a bead finds itself at a node of the vibration, a place where the periodic, sinusoidal undulation is actually quiescent. — Eric J. Heller, Why You Hear What You Hear- An…, 794

Categorization

• DEFINE: Defines the term ‘node’ in vibration via the concrete bead example.
• XREF: connects to: A string’s nth mode has n+1 nodes and n antinodes — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1081