— rachidian /reuh kid"ee euhn/ , rachial /ray"kee euhl/ , rachidial , adj.
/ray"kis/ , n. , pl. rachises, rachides /rak"i deez', ray"ki-/ .
1. Bot.
a. the axis of an inflorescence when somewhat elongated, as in a raceme.
b. (in a pinnately compound leaf or frond) the prolongation of the petiole along which the leaflets are disposed.
c. any of various axial structures.
2. Ornith. the part of the shaft of a feather bearing the web. See illus. under feather .
3. Anat. See spinal column .
Also, rhachis .
[ 1775-85; rháchis spine, ridge, backbone ]