OPTI-CUS, OPTIC. [Gr. +optomai+, _optomai_, to see.] Relating to the eye.

OR-BICU-LAR. [L. _orbis_, a circle.] Circular.

OR-BIC-U-LARIS. A name applied to several muscles.

ORGAN. A part of the system destined to exercise some particular function.

ORI-GIN. Commencement; source.

OS. [L.] A bone; the mouth of any thing.

ORIS. [L. _os_, _oris_.] Of the mouth.

OS HY-OIDES. [Gr. See HYOID.] The name of the bone at the base of the tongue.

OSMA-ZOME. [Gr. +osm+, _osm_, smell, and +zmos+, _zmos_, broth.]

A principle obtained from animal fibre which gives the peculiar taste to broth.

OSSA. [L., plural of _os_, bone.] Bones.

OSSE-OUS. Pertaining to bones.

OS-SI-FI-CATION. The formation of bones in animals.

OSSI-FY. [L. _ossa_, bones, and _facio_, to make.] To convert into bone.

OSSIS. Of a bone.

O-VALE. [L.] The shape of an egg.

OX-ALIC. Pertaining to sorrel. _Oxalic acid_ is the acid of sorrel.

It is composed of two equivalents of carbon and three of oxygen.

OXY-GEN. A permanently elastic fluid invisible and inodorous. One of the components of atmospheric air.

PA-LATUM. [L.] The palate; the roof of the mouth.

PAL-PE-BRARUM. [L. _palpebra_, the eyelid.] Of the eyelids.

PALMAR. [L. _palma_, the palm.] Belonging to the hand.

PAL-MARIS. A term applied to some muscles attached to the palm of the hand.

PANCRE-AS. [Gr. +pan+, _pan_, all, and +kreas+, _kreas_, flesh.] The name of one of the digestive organs.

PAN-CRE-ATIC. Belonging to the pancreas.

PA-PILLA, -. [L.] Small conical prominences.

PA-RALY-SIS. Abolition of function whether of intellect, sensation, or motion.

PA-RENCHY-MA. [Gr. +parenche+, _parengche_, to pour through.] The substance contained between the blood vessels of an organ.

PA-ROTID. [Gr. +para+, _para_, near, and +tos+, _tos_, the gen. of +ous+, _ous_, the ear.] The name of the largest salivary gland.

PA-TELLA, -. [L.] The knee-pan.

PA-THETI-CUS, -CI. [Gr. +pathos+, _pathos_, pa.s.sion.] The name of the fourth pair of nerves.

PECTUS. [L.] The chest.

PECTO-RAL. Pertaining to the chest.

PEC-TO-RALIS. Belonging to the chest.

PEDIS. [L., gen. of _pes_, the foot.] Of the foot.

PELI-TONGS. A term applied to ma.s.ses of fat.

PELLI-CLE. [L., dim. of _pellis_, the skin.] A thin skin or film.

PELVIC. Relating to the pelvis.

PELVIS. [L.] The basin formed by the large bones at the lower part of the abdomen.

PENNI-FORM. [L. _penna_, a feather.] Having the form of a feather, or quill.

PER-I-CARDI-UM. [Gr. +peri+, _peri_, around, and +kardia+, _kardia_, the heart.] A membrane that encloses the heart.

PER-I-CHONDRI-UM. [Gr. +peri+, _peri_, around, and +chondros+, _chondros_, cartilage.] A membrane that invests cartilage.

PER-I-CRANI-UM. [Gr. +peri+, and +kranion+, _kranion_, the cranium.]

A membrane that invests the skull.

PERMA-NENT. Durable; lasting.

PER-I-STALTIC. [Gr. +peristell+, _peristello_, to involve.] A movement like the crawling of a worm.

PER-SPI-RATION. [L. _per_, through, and _spiro_, to breathe.] The excretion from the skin.

PHALANX, -GES. [Gr. +phalanx+, _phalanx_, an army.] Three rows of small bones forming the fingers or toes.

PHA-LANGI-AL. Belonging to the fingers or toes.

PHA-RYNGE-AL. Relating to the pharynx.

PHARYNX. [Gr. +pharunx+, _pharunx_.] The upper part of the oesophagus.