undulation

UK: /ˌʌndjʊˈleɪʃən/

US: /ˌʌndʒəˈleɪʃən, -djə-, -də-/

US: (un′jə lā′shən, un′dyə-, -də-)

WordReference Random House Unabridged Dictionary of American English © 2026

un•du•la•tion  (un′jə lā′shən, un′dyə-, -də-), n. 

1. an act of undulating;
   a wavelike motion.
2. a wavy form or outline.
3. one of a series of wavelike bends, curves, or elevations.
4. [Physics.]
   • Physics a wave.
   • Physics the motion of waves.

• undul(ate) + -ation 1640–50

Collins Concise English Dictionary © HarperCollins Publishers::

undulation / ˌʌndjʊˈleɪʃən/ noun

1. the act or an instance of undulating
2. any wave or wavelike form, line, etc

WordReference Random House Learner's Dictionary of American English © 2026

un•du•late /v. ˈʌndʒəˌleɪt, ˈʌndyə-, -də-; adj. -lɪt, -ˌleɪt/   v., -lat•ed, -lat•ing, adj. 
v. 

1. to move with a wavelike motion: [no object]
   The serpent undulated across the grass.
   [~ + object]
   She undulated her hips as she performed the dance.
2. to have a wavy form or surface:
   [no object] The hills undulated in the distance.
3. (of a sound) to rise and fall in pitch:
   [no object] A siren undulated.

adj. 

4. Also, ˈun•duˌlat•ed. having a wavelike form or surface;
   wavy.

un•du•la•tion /ˌʌndʒəˈleɪʃən, -dyə-, -də-/  n. 

[uncountable] the sea's undulation.

[countable] the undulations of the dancer's hips.

WordReference Random House Unabridged Dictionary of American English © 2026

un•du•late  (v. un′jə lāt′, un′dyə-, -də-;adj. un′jə lit, -lāt′, un′dyə-, -də-), v., -lat•ed, -lat•ing, adj. 
v.i. 

1. to move with a sinuous or wavelike motion;
   display a smooth rising-and-falling or side-to-side alternation of movement:
   The flag undulates in the breeze.
2. to have a wavy form or surface;
   bend with successive curves in alternate directions.
3. (of a sound) to rise and fall in pitch:
   the wail of a siren undulating in the distance.

v.t. 

4. to cause to move in waves.
5. to give a wavy form to.

adj. 

6. Also, un′du•lat′ed. having a wavelike or rippled form, surface, edge, etc.;
   wavy.

• Latin undulātus waved, equivalent. to und(a) wave + -ul(a) -ule + -ātus -ate¹
• 1650–60

un′du•la′tor, n.