popular name for a bacterium or other extremely small living being, 1878, from French microbe, "badly coined ... by Sédillot" [Weekley] in 1878 from Latinized form of Greek mikros "small" (see micro-) + bios "life" (from PIE root *gwei- "to live"). Intended to mean literally "a small living being," the use of bios is incorrect, as in modern science generally (see bio-); in Greek the compound would mean "short-lived."
"living in the blood" (as a parasite does), by 1889, from Latin sanguis "blood" (see sanguinary) + colere "to inhabit" (see colony). Also, with classical stem, sanguinicolous.
c. 1600, "of or pertaining to natural science" (a sense now obsolete), from physiology + -ical. From 1814 as "of or pertaining to physiology, relating to the functions and properties of living bodies." Related: Physiologically.