Old English spon "chip, sliver, shaving, splinter of wood," from Proto-Germanic *spe-nu- (source also of Old Norse spann, sponn "chip, splinter," Swedish spån "a wooden spoon," Old Frisian spon, Middle Dutch spaen, Dutch spaan, Old High German span, German Span "chip, splinter"), from PIE *spe- (2) "long, flat piece of wood" (source also of Greek spathe "spade," also possibly Greek sphen "wedge").
As the word for a type of eating utensil, c. 1300 in English (in Old English such a thing might be a metesticca), in this sense supposed to be from Old Norse sponn, which meant "spoon" as well as "chip, tile." The "eating utensil" sense is specific to Middle English and Scandinavian, though Middle Low German spon also meant "wooden spatula." To be born with a silver spoon in one's mouth is from at least 1719 (Goldsmith, 1765, has: "one man is born with a silver spoon in his mouth, and another with a wooden ladle").
apparently an early Middle English merger of three related Old English nouns, flota "boat, fleet," flote "troop, flock," flot "body of water, sea;" all from the source of float (v.). The early senses were the now-mostly-obsolete ones of the Old English words: "state of floating" (early 12c.), "swimming" (mid-13c.); "a fleet of ships; a company or troop" (c. 1300); "a stream, river" (early 14c.). From c. 1300 as an attachment for buoyancy on a fishing line or net; early 14c. as "raft." Meaning "platform on wheels used for displays in parades, etc." is from 1888, probably from earlier sense of "flat-bottomed boat" (1550s). As a type of fountain drink, by 1915.
Float.—An ade upon the top of which is floated a layer of grape juice, ginger ale, or in some cases a disher of fruit sherbet or ice cream. In the latter case it would be known as a "sherbet float" or an "ice-cream float." ["The Dispenser's Formulary: Or, Soda Water Guide," New York, 1915]
Few soda water dispensers know what is meant by a "Float Ice Cream Soda." This is not strange since the term is a coined one. By a "float ice cream soda" is meant a soda with the ice cream floating on top, thus making a most inviting appearance and impressing the customer that you are liberal with your ice cream, when you are not really giving any more than the fellow that mixes his ice cream "out of sight." [The Spatula, Boston, July, 1908]