rocker

Etymology

From Middle English rokker, rockere, rokkere, equivalent to rock + -er.

noun

1. A curved piece of wood attached to the bottom of a rocking chair or cradle that enables it to rock back and forth.
   The cradle-rockers had done hard duty for so many years, under the weight of so many children, on that flagstone floor, that they were worn nearly flat, in consequence of which a huge jerk accompanied each swing of the cot, flinging the baby from side to side like a weaver's shuttle, as Mrs Durbeyfield, excited by her song, trod the rocker with all the spring that was left in her after a long day's seething in the suds. 1891, Thomas Hardy, Tess of the d'Urbervilles, volume 1, London: James R. Osgood, McIlvaine and Co., page 30
2. A rocking chair.
   A few days before he turned 80 2021, “Buy Dirt”, in Buy Dirt, performed by Jordan Davis
3. (surfing) The lengthwise curvature of a surfboard. (More rocker is a more curved board.)
   All modern surfboards share a similar rocker design — Bruce Jones https://web.archive.org/web/20051212041317/http://www.brucejones.com/longboar.htm
4. The breve below as in ḫ.
   Like the editors of other Elamite texts, I omit the diacritic rocker from h in Elamite and from H in logograms in Elamite texts. I retain the rocker in ḫ and Ḫ in Sumerian and Akkadian. 1984, Matthew Wolfgang Stolper, Texts from Tall-i Malyan Elamite Administrative Texts (1972–1974) (Occasional Publications of the Babylonian Fund; 6), University of Pennsylvania Press, page XVII
   Although the exact sound value of s remains uncertain, and there is only one such sibiliant in Hittite, it is traditionally transliterated with a so-called haček: š. This should not be taken, however, as evidence that it was a palatal sound (as sh in show). The same is true for the traditional “rocker” under the laryngeal ḫ: there is no other h-sign, and the diacritic is not strictly necessary. 2011, Theo van den Hout, The Elements of Hittite, Cambridge University Press, page 13
   Semitistic transliteration systems […] a number of features are common to most of them: […] ḫ (“h” with a “rocker,” conventionally called “hooked h”) for the voiceless velar/uvular fricative, IPA [x]/[χ], […] 2019, John Huehnergard, “Proto-Semitic”, in Huehnergard, John and Na'ama Pat-El, editors, The Semitic Languages, 2nd edition, Routledge, page 15
5. Someone passionate about rock music.
6. A musician who plays rock music.
7. (informal) A rock music song.
   "Girls & Boys" is […] also a tart, sneering rocker, full of ingenious musical gestures […] September 2010, Pitchfork Media, The Top 200 Tracks of the 1990s https://web.archive.org/web/20110218044518/http://pitchfork.com/features/staff-lists/7852-the-top-200-tracks-of-the-1990s-50-21/3
8. One who rocks something.
9. (UK) A member of a British subculture of the 1960s, opposed to the mods, who dressed in black leather and were interested in 1950s music.
10. Any implement or machine working with a rocking motion, such as a trough mounted on rockers for separating gold dust from gravel, etc., by agitation in water.
11. A tool with small teeth that roughens a metal plate to produce tonality in mezzotints.
12. A rocking horse.
13. A rocker board.
14. A skate with a curved blade, somewhat resembling in shape the rocker of a cradle.
15. A kind of electrical switch with a spring-loaded actuator.
16. (engineering) A rock shaft.
17. (military) A curved line accompanying the chevrons that denote rank, qualifying the rank with a grade.
    Cadet Sergeant First Class: 3 Chevrons and 2 rockers. Cadet Master Sergeant: 3 Chevrons and 3 rockers. Cadet First Sergeant: 3 Chevrons, 3 rockers with a diamond inset. 2000, Mark Collantes, The Academy, page 66