sinu-, sin-

1. Lithe and graceful, especially making graceful winding or curving movements; such as, the dancer had many sinuous movements.
2. Full of bends and curves with reference to the sinuous course of a stream.
3. Indirect and devious; characterized by many curves or turns; winding.

1. A serpentine or wavy form.
2. Having curves.

1. An air-filled cavity in a dense portion of a skull bone.

The sinuses are formed in four right-left pairs: The frontal sinuses are positioned behind the forehead, while the maxillary sinuses are behind the cheeks.

The sphenoid and ethmoid sinuses are deeper in the skull behind the eyes and maxillary sinuses.

The sinuses are lined by mucous-secreting cells. Air enters the sinuses through small opening in bone called ostia. If an ostium is blocked, air cannot pass into the sinus and likewise mucous cannot drain out.

2. A channel permitting the passage of blood or lymph fluid that is not a blood or lymphatic vessel; such as, the sinuses of the placenta.
3. A tract or fistula leading to a cavity which may be filled with pus.
4. Etymology: "abscess, sore", from Middle Latin sinus, from Latin sinus, "bend, fold, curve". Meaning "hollow curve or cavity in the body" is attested from 1672. Sinusitis, "inflammation of a sinus" is recorded from 1896.

1. Inflammation of the sinuses, or a sinus; especially, in the nasal region.
2. Inflammation of a sinus, usually a paranasal sinus; it may be purulent or nonpurulent, acute or chronic.

1. A small blood vessel or cavity in the tissue of an organ; such as, the liver, heart, or pancreas.
2. Any of the venous cavities through which blood passes in various glands and organs; such as, the adrenal gland and the liver.