si·nus 
(sīnəs)
(sīnəs)n.
1. A depression or cavity formed by a bending or curving.
2. Anatomy
a. A dilated channel or receptacle containing chiefly venous blood.
b. Any of various air-filled cavities in the bones of the skull, especially one communicating with the nostrils.
3. Medicine A fistula leading from a pus-filled cavity.
4. Botany A recess or indentation between two lobes or segments, as of a leaf.
[Middle English, hollow in the body, from Medieval Latin, from Latin, curve, hollow.]
sinus- Indo-European root: kreus-
- Indo-European root: kreuə-
- Indo-European root: ksun
- Indo-European root: kwe
- Indo-European root: kwei-
- Indo-European root: kwei-
- Indo-European root: kweit-
- Indo-European root: kweiə-
- Indo-European root: kwel-
- Indo-European root: kwel-
- Indo-European root: kwen-
- Indo-European root: kwent(h)-
- Indo-European root: kwer-
- Indo-European root: kwes-
- Indo-European root: kwetwer-
- Indo-European root: kwo-
- Indo-European root: kwon-
- Indo-European root: kwrep-
- Indo-European root: kwr̥mi-
- Indo-European root: kwēt-
- Indo-European root: kā-
- Indo-European root: kō-
- Indo-European root: laks-
- Indo-European root: las-
- Indo-European root: lau-