share (n.1)

"portion," Old English scearu "a cutting, shearing, tonsure; a part or division," related to sceran "to cut," from Proto-Germanic *skeraz (source also of Old High German scara "troop, share of forced labor," German Schar "troop, band," properly "a part of an army," Old Norse skör "rim"), from PIE root *sker- (1) "to cut."

Meaning "part of the capital of a joint stock company" is first attested c. 1600. Share and share alike attested from 1560s. The same Old English noun in the sense "division" led to an obsolete noun share "fork ('division') of the body at the groin; pubic region" (late Old English and Middle English); hence share-bone "pubis" (early 15c.).

share (n.2)

"iron blade of a plow," Old English scear, scær "plowshare," properly "that which cuts," from Proto-Germanic *skeraz (source also of Old Frisian skere, Middle Low German schar, Old High German scar, German Schar, Dutch ploegschaar, Middle High German pfluocschar), from PIE root *sker- (1) "to cut."

share (v.)

1580s, "to apportion to someone as his share; to apportion out to others; to enjoy or suffer (something) with others," from share (n.1). Meaning "to divide one's own and give part to others" is recorded from 1590s. Meaning "confess one's sins openly" (1932, implied in sharing) is from "the language of Moral Rearmament" [OED]. Related: Shared; sharer; sharing.

Definitions of share
share (v.)
have in common;
Our children share a love of music
The two countries share a long border
share (v.)
use jointly or in common;
share (v.)
have, give, or receive a share of;
We shared the cake
Synonyms: partake / partake in
share (v.)
give out as one's portion or share;
Synonyms: divvy up / portion out / apportion / deal
share (v.)
I'd like to share this idea with you
share (n.)
assets belonging to or due to or contributed by an individual person or group;
he wanted his share in cash
Synonyms: portion / part / percentage
share (n.)
any of the equal portions into which the capital stock of a corporation is divided and ownership of which is evidenced by a stock certificate;
he bought 100 shares of IBM at the market price
share (n.)
the allotment of some amount by dividing something;
death gets more than its share of attention from theologians
Synonyms: parcel / portion
share (n.)
the effort contributed by a person in bringing about a result;
they all did their share of the work
Synonyms: contribution / part
share (n.)
a sharp steel wedge that cuts loose the top layer of soil;
Synonyms: plowshare / ploughshare