1660s, "average, middling," from medium (n.). The Latin adjective was medius. Meaning "intermediate" is from 1796. As a designation of size or weight, by 1711. As a designation of cooked meat between well-done and rare, it is attested from 1931; earlier was medium-rare (1881).
"canoe made from the trunk of a hollowed-out tree," 1660s, from French pirogue, from a West Indian language, probably from Galibi (a Carib language) piragua "a dug-out." Compare Spanish piragua (1530s), which might be the intermediate form for the French word. The word was extended to all type of native open boats.
1766, in a British sense, "class of people socially intermediate between the aristocratic and the laboring classes, the community of untitled but well-bred or wealthy people," from middle (adj.) + class (n.). As an adjective, "pertaining to the middle class," by 1857, with reference to education. Nares reports menalty as an early word for "the middle class" (1540s).
salutation in parting, also goodbye, good bye, good-by, 1590s, from godbwye (1570s), a contraction of God be with ye (late 14c.), influenced by good-day, good evening, etc. As a noun from 1570s. Intermediate forms in 16c. include God be wy you, God b'uy, God buoye, God buy, etc.
subatomic particle, 1939, from Greek mesos "middle" (from PIE root *medhyo- "middle") + subatomic particle suffix -on. Earlier mesotron (1938). So called for being intermediate in mass between protons and electrons. An earlier use of the word, from the Greek noun meson "center," meant "the medial plane which divides the body into two equal and symmetrical parts" (by 1883).
"pertaining to or situated in the middle, occupying a middle or intermediate position," 1590s, from French médian (15c.) and directly from Latin medianus "of the middle," from medius "in the middle" (from PIE root *medhyo- "middle"). Originally anatomical, of veins, arteries, nerves; general use is by 1640s. Median strip "narrow strip (paved or not) between lanes of a divided road" is by 1939, American English.