What does the word "dynamics" mean in the context of proteins or biomolecules in general?

Question

What does it mean by “dynamics” when we say “dynamics of protein” or “dynamics of biomolecules”? For instance, McCammon's paper has the title "Protein Dynamics" [1]. What does the word “dynamics” mean in this case?

Please, supply me with at least one reference.

Reference

1. McCammon, J. A. Protein Dynamics. Rep. Prog. Phys. 1984, 47 (1), 1–46. DOI: 10.1088/0034-4885/47/1/001.

Answer 1

From Lottspeich' Bioanalytics, subsection Determination of Protein Dynamics [1, p. 463] (strong emphasis mine):

Determination of Protein Dynamics

Proteins are not rigid, static entities, but rather exist as ensembles of conformations. The internal motions, which give rise to transitions between different structural states, are collectively referred to as protein dynamics and occur on a wide range of time scales (ns–s). Protein dynamics play crucial roles in protein functions particularly for the interaction with binding partners, in enzyme catalysis, and in allosteric regulation. Luckily, many NMR spectroscopic parameters depend both on the mobility of the whole molecule (translational or rotational motions) and on internal motions (transitions between different conformations or bond rotations), providing insight into a wide variety of dynamic processes ranging from fast fluctuations (lasting picoseconds) to slower conformational changes (lasting microseconds or more).

Protein dynamics studies have been used in biochemistry for studying genomics [2], enzymology [3] and many other areas, including GPCRs activity research which lead to the 2012 Nobel Prize in chemistry.

References

1. Bioanalytics: Analytical Methods and Concepts in Biochemistry and Molecular Biology, 1st ed.; Lottspeich, F., Engels, J. W., Eds.; Wiley: Weinheim, 2018. ISBN 978-3-527-33919-8.
2. Misteli, T. Protein Dynamics: Implications for Nuclear Architecture and Gene Expression. Science 2001, 291 (5505), 843–847. DOI: 10.1126/science.291.5505.843.
3. Klinman, J. P.; Kohen, A. Hydrogen Tunneling Links Protein Dynamics to Enzyme Catalysis. Annu Rev Biochem 2013, 82, 471–496. DOI: 10.1146/annurev-biochem-051710-133623.