What is the etymology of "-cade" as in motorcade or cavalcade?
Solution 1:
Etymonline sources cavalcade as a single word, part of which became a suffix.
cavalcade (n.) 1590s, via Middle French cavalcade (15c.), [...] from Latin caballus (see cavalier). Literally, “a procession on horseback;” in 20c. -cade came to be regarded as a suffix and taken to form motorcade (1913), etc.
Cavalcade is the source of the suffix.
Similar to the way -gate (from Watergate) became a suffix meaning “scandal about” (subject specified by the word to which it is attached), -cade came to mean “a procession of” (subject specified by the word to which it is attached).
There is no standalone traceable meaning to the suffix beyond “it was part of a word that meant something similar” now available to affix in other contexts.
Solution 2:
The latin verb ending -icare forms verbs from nouns. So from the (late, vulgar) latin word caballus one get caballicare directly translated that means "to 'horse'", which is how a late latin speaker would say "to ride a horse"
Digging deeper, the ic of icare is from the noun ending i and a suffix that forms adjectives -cus, the -are of -icare is the usual present infinitive verbal ending of latin verbs which end in -o.
In Italian, -icare is still used to form verbs from nouns, for example neve (snow) gives nevicare (to snow).
From here the etymology dictionary gives details. From vulgar Latin caballicare the Italians got cavalcare (by regular sound shifts) which is gives a noun cavalcata. That became cavalcade in French, which was borrowed in English in the late 16th century.
All in all it is a bit of a mishmash. The "c" of cade is a fragment of one latin suffix, and the "ade" is a change pronunciation of the latin verbal ending "-are"
Solution 3:
-cade is a suffix abstracted from cavalcade:
a combining form extracted from cavalcade, used with the meaning “procession” in the formation of compound words:
- motorcade (1909); tractorcade; autocade(1922); acquacade(1937).
(Dictionary.com)(Etymonline)