plexus n.

Proto-Indo-European root meaning "to plait." It is an extended form of root *pel- (2) "to fold."

It forms all or part of: accomplice; application; apply; complex; complexion; complicate; complication; complicity; deploy; display; duplex; duplicate; duplicity; employ; explicate; explicit; exploit; flax; implex; implicate; implication; implicit; imply; multiply; perplex; perplexity; plait; plash (v.2) "to interlace;" pleat; -plex; plexus; pliable; pliant; plie; plight (n.1) "condition or state;" ply (v.1) "work with, use;" ply (v.2) "to bend; ply (n.) "a layer, fold;" replica; replicate; replication; reply; simplex; splay; triplicate.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit prasna- "turban;" Greek plekein "to plait, braid, wind, twine," plektos "twisted;" Latin plicare "to lay, fold, twist," plectere (past participle plexus) "to plait, braid, intertwine;" Old Church Slavonic plesti "to braid, plait, twist," Russian plesti; Gothic flahta "braid;" Old Norse fletta, Old High German flehtan "to plait;" Old English fleax "cloth made with flax, linen."

mid-15c., "of, pertaining to, or determined by the sun," from Latin solaris "of the sun," from sol "sun" (from PIE root *sawel- "the sun"). Meaning "living room on an upper story" (also sollar) is from Old English, from Latin solarium (see solarium). For "of or proceeding from the sun," the earlier word was Old English sunlic, Middle English sonneli. Solific (1550s) also has been used.

The meaning "operated by means of the sun or its heat" is from 1740; solar power is attested from 1915, solar cell as a photovoltaic device from 1955, solar panel, designed to absorb the sun's rays, is from 1964. The astronomical solar system "sun and the bodies revolving round or dependent on it" is attested from c. 1704; solar wind is so called from 1958.

Solar plexus (1771) "complex of nerves in the pit of the stomach," apparently so called from its central position in the body (see plexus).

Latin plural of ganglion. Related: Gangliac, ganglial, gangliar, ganglious. The larger ones are plexuses (see plexus).