What is a wave?

What is a wave? Is a wave a “thing”, or is it merely a way of speaking about pieces of stuff changing in a certain way in time? This is related to William of Ockham’s ideas about motion, that “motion” does not deserve to be thought about as a thing but merely as a convenient way of discussing the position of things at different points in time. The following are some references I assembled about waves. Lamb [24, p. 369, §236] Preston [33, p. 412, §289] Basset [2, p. 163, §405] Whewell [49, Book IV] Whewell [50, Book VIII] Russo [37, p. 229] Crombie [9, p. 126] Philoponus [29, p. 149] De anima [17, §447] Einstein and Infeld [16, p. 100] Vitruvius [21, p. 11] Thagard [45, p. 39] Thorndike [46, p. 32] Pretor-Pinney [34, pp. 35, 81, 161, 269] Truesdell [48, p. 71] and [47, pp. CXXI–CXXIII] Clagett [7, p. 74] Hofstadter and Sander [20, p. 209], Sambursky [40, pp. 138–141] and [41, pp. 89, 100–104] and [39, p. 22–29] Needham [28, pp. 8-10] Beare [3, pp. 93–95] Hankinson [19, p. 240]