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dim (adj.)[dim 词源字典]: Old English dimm "dark, gloomy, obscure," from Proto-Germanic *dimbaz (cognates: Old Norse dimmr, Old Frisian dim, Old High German timber "dark, black, somber"). Not known outside Germanic. Slang sense of "stupid" is from 1892. Related: Dimly; dimness.[dim etymology, dim origin, 英语词源]
float (v.): late Old English flotian "to rest on the surface of water" (intransitive; class II strong verb; past tense fleat, past participle floten), from Proto-Germanic *flotan "to float" (cognates: Old Norse flota, Middle Dutch vloten, Old High German flozzan, German flössen), from *flot-, from PIE *pleud-, extended form of root *pleu- "to flow" (see pluvial).

Meaning "drift about, hover passively" is from c. 1300. Transitive sense of "to lift up, cause to float" (of water, etc.) is from c. 1600; that of "set (something) afloat" is from 1778 (originally of financial operations). Of motion through air, from 1630s. Meaning "hover dimly before the eyes" is from 1775. Related: Floated; floating. A floating rib (by 1802) is so called because the anterior ends are not connected to the rest.
glimmer (v.): late 14c., "to shine brightly;" early 15c., "to shine dimly," perhaps from or related to Middle Dutch glimmen, Middle Low German glimmern, from an extended (frequentative?) form of Proto-Germanic *glim-, root of Old English glæm "brightness" (see gleam (n.)). Sense shifted 15c. to "shine faintly." Compare Dutch glimmeren, German glimmeren "to shine dimly." Related: Glimmered; glimmering.
twilit: "Dimly illuminated by or as if by twilight", Mid 19th century: past participle of the literary verb twilight.