An Etymological Dictionary of Astronomy and Astrophysics

1. (Adj.) Being or acting at the middle place or stage, or between extremes.
   

2a) (n.) A person who acts between others; something intermediate.

2b) Chemistry: A molecular entity that is formed (directly or indirectly) from the reactants and reacts further to give (either directly or indirectly) the products of a chemical reaction (PAC, 1996, 68, 149, A glossary of terms used in chemical kinetics, including reaction dynamics, IUPAC Recommendations 1996).

See also:
→ intermediate boson, → intermediate frequency, → intermediate infrared, → intermediate-mass black hole, → intermediate-mass protostar, → intermediate-mass star.

Etymology (EN): Intermediate, from M.L. intermediatus “lying between,” from L. intermedius “that which is between,” from → inter- “between”

• medius “located in the middle;” PIE root *medhyo- “middle;” cf. Pers. miyân, as below; Av. maidiia-, Skt. mádhya-; Gk. medos, messos “middle;”

Etymology (PE): Miyâni, adj. of miyân “within, between, center,” from Mid.Pers. mayân “middle; among, between,” Av. maidiia- “middle, the middle,” maiδiiāna- “middle, center;” cf. Skt. mádhya- “middle, located in the middle;” G.H.G. mitti “located in the middle.”
Andarmiyâni, adj. of andarmiyân “in the middle,” from andar-, → inter-, + miyân, as above.
Miyânji “intermediary, mediator,” from Mid.Pers. mayânjig, from mayân.