rachis

[rey-kis] /ˈreɪ kɪs/

noun, plural rachises, rachides

[rak-i-deez, rey-ki-] /ˈræk ɪˌdiz, ˈreɪ kɪ-/ (Show IPA)

Botany.

the axis of an inflorescence when somewhat elongated, as in a raceme.
(in a pinnately compound leaf or frond) the prolongation of the petiole along which the leaflets are disposed.
any of various axial structures.

Ornithology. the part of the shaft of a feather bearing the web.

Anatomy, spinal column.

Also, rhachis.

Origin

1775-85; < Neo-Latin < Greek rháchis spine, ridge, backbone

Related forms

rachidian

[ruh-kid-ee-uh n] /rəˈkɪd i ən/ (Show IPA), rachial

[rey-kee-uh l] /ˈreɪ ki əl/ (Show IPA), rachidial, adjective

Examples from the web for rachis

The rachis has a swollen base, and the entire bipinnately compound leaf is arranged in alternate fashion along the stout twig.
The spikelets are borne on short racemes which branch from the rachis in paniculate fashion.
Spikelet cylindric, placed flatwise at each joint of the rachis and fitting into it.

British Dictionary definitions for rachis

rachis

/ˈreɪkɪs/

noun (pl) rachises, rhachises, rachides, rhachides (ˈrækɪˌdiːz; ˈreɪ-)

(botany) the main axis or stem of an inflorescence or compound leaf

(ornithol) the shaft of a feather, esp the part that carries the barbs

another name for spinal column

Derived Forms

rachial, rhachial (ˈreɪkɪəl), rachidial, rhachidial (rəˈkɪdɪəl) adjective

Word Origin

C17: via New Latin from Greek rhakhis ridge

rachis in Medicine

rachis ra·chis (rā'kĭs)
n. pl. ra·chis·es or rach·i·des (rāk'ĭ-dēz', rā'kĭ-)
See spinal column.

rachis in Science

rachis

(rā'kĭs)
Plural rachises or rachides (rāk'ĭ-dēz', rā'kĭ-)
A main axis or shaft, such as the main stem of an inflorescence, the stalk of a pinnately compound leaf, the shaft of a feather, or the spinal column.