Yours, Etc.: Origins and Uses of 8 Sign-Offs
"one who tests," 1660s, agent noun from test (v.).
"canopy over a bed," late 14c., from Medieval Latin testerium, from testera "head stall," from Late Latin testa (capitis) "skull," from Latin, literally "earthenware, pot." The "head" sense (originally merely humorous) is the source of tester in obsolete senses of "piece of armor for the head" (late 14c.) and "coin of Henry VIII" (1546), the first English coin to bear a true portrait. For sense development, cf. Old English cuppe "cup" from source of German kopf "head."
canopy, usually of carved or cloth-draped wood, over a bed, tomb, pulpit, or throne. It dates from the 14th century and is usually made of the same material as the object it covers. It can be supported either by four posts, by two posts at the foot and a headpiece at the back, or by suspension from the ceiling. The edges may overhang and in some cases are decorated with incised work or a fabric valance. The word, derived from the late Latin testa ("head"), came into use in the Middle Ages, originally referring only to the vertical headpiece.