shaking

The core verb 'shake' originates from the Old English 'sceacan', meaning "to move something quickly to and fro." This Old English term is traced back to the Proto-Germanic 'skakaną', which carried a similar sense of shaking or waving. The Proto-Germanic root is further linked to the Proto-Indo-European '(s)keg-', meaning "to jump, move," illustrating a conceptual link between sudden, jumping motion and the vibratory action of shaking. The addition of the '-ing' suffix, a stable element from Old English '-ung'/-'ing', transforms the action into a descriptive adjective or a noun denoting the process or result of that action, giving us the modern word 'shaking'.

The word 'shaking' is the present participle or gerund form of the verb 'shake'. The root 'shake' is a simplex word of Old English origin, and the suffix '-ing' is a productive suffix from Old English used to form present participles, gerunds, and deverbal nouns/adjectives.