いし

Etymology 1
Compound of and. As -i was archaic even in Old Japanese, -si was attached to supplement it.

Particle

 * 1) emphatic nominative case marker
 * 2) * 797: Shoku Nihongi (edict 13)
 * 3) * 797: Shoku Nihongi (edict 13)
 * 1) * 797: Shoku Nihongi (edict 13)
 * 1) * 797: Shoku Nihongi (edict 13)

Etymology 2
Reading for various terms.

Noun

 * 1)  stone