sternum (n.)

"of or pertaining to the sternum, clavicle, and mastoid process," 1826, medical Latin, from sterno- "sternum," Greek sternon "breast, breastbone," or Latin sternum (see sternum) + Latinized Greek kleis (see clavicle) + mastoid.

instrument for examining the chest, 1820, from French stéthoscope, coined 1819 by its inventor, French physician René-Théophile-Hyacinthe Laënnec (1781-1826), from Greek stēthos "chest, breast" + -scope. Greek stēthos is perhaps related to sternon (see sternum); it meant "front of the chest," and was only rarely used of a woman's breasts, but in Modern Greek it became the preferred polite term. Related: Stethoscopic; stethoscopically; stethoscopy.

*sterə-, also *ster-, Proto-Indo-European root meaning "to spread."

It forms all or part of: consternate; consternation; construct; construction; destroy; destruction; industry; instruct; instruction; instrument; obstruct; obstruction; perestroika; prostrate; sternum; sternocleidomastoid; strain (n.2) "race, stock, line;" stratagem; strategy; strath; strato-; stratocracy; stratography; stratosphere; stratum; stratus; straw; stray; street; strew; stroma; structure; substrate; substratum; substructure.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit strnoti "strews, throws down;" Avestan star- "to spread out, stretch out;" Greek stronymi "strew," stroma "bedding, mattress," sternon "breast, breastbone;" Latin sternere "to stretch, extend;" Old Church Slavonic stira, streti "spread," strana "area, region, country;" Russian stroji "order;" Gothic straujan, Old High German strouwen, Old English streowian "to sprinkle, strew;" Old English streon "strain," streaw "straw, that which is scattered;" Old High German stirna "forehead," strala "arrow, lightning bolt;" Old Irish fo-sernaim "spread out," srath "a wide river valley;" Welsh srat "plain."