1510s, "to prick slightly," from prickle (n.). By 1855 as "to cause a prickling sensation in." Related: Prickled; prickling.
late 14c., "likely, reasonable, plausible, having more evidence for than against," from Old French probable "provable, demonstrable" (14c.), from Latin probabilis "worthy of approval, pleasing, agreeable, acceptable; provable, that may be assumed to be believed, credible," from probare "to try, to test" (see prove). As a legal term, probable cause "reasonable cause or grounds" is attested from 1670s.
Probable cause (used with reference to criminal prosecutions), such a state of facts and circumstances as would lead a man of ordinary caution and prudence, acting conscientiously, impartially, reasonably, and without prejudice, upon the facts within his knowledge, to believe that the person accused is guilty. [Century Dictionary]
"substance that produces coagulation," 1770, from Latin coagulantem (nominative coagulans), present participle of coagulare "cause to curdle" (see coagulate).