| HOLOPHOTES | • holophotes n. Plural of holophote. • HOLOPHOTE n. an apparatus by which all the light from a lighthouse is thrown in the required direction. |
| HOMOEOPATH | • homoeopath n. Alternative spelling of homeopath. • homœopath n. Obsolete spelling of homoeopath. • HOMOEOPATH n. a person who believes in or practises homoeopathy, also HOMEOPATH, HOMEOPATHIST, HOMOEOPATHIST. |
| OCTOTHORPE | • octothorpe n. (Chiefly US, typography) The hash or square symbol (#), used mainly in telephony and computing. |
| OPTOPHONES | • optophones n. Plural of optophone. • OPTOPHONE n. a device transforming light into sound. |
| ORTHOPNOEA | • orthopnoea n. Shortness of breath when lying flat, causing the person to have to sleep propped up in bed or sitting in a chair. • orthopnœa n. Obsolete spelling of orthopnoea. • ORTHOPNOEA n. the ability to breathe in an upright position only. |
| ORTHOSCOPE | • orthoscope n. An instrument for examining the interior of an eye. • orthoscope n. An instrument for drawing projections of a skull. • ORTHOSCOPE n. a nineteenth century instrument for viewing the fundus of the eye through a layer of water, which eliminates distortion caused by the cornea. |
| PHOTODIODE | • photodiode n. (Electronics) A semiconductor two-terminal component whose electrical characteristics are light-sensitive. • PHOTODIODE n. a two-electrode semiconductor device. |
| PHOTONOVEL | • photonovel n. A story illustrated with photographs and text captions. • PHOTONOVEL n. a novel in the form of a series of photographs with speech balloons. |
| PHOTOPHOBE | • PHOTOPHOBE n. a plant that shuns or avoids light. |
| PHOTOPHONE | • photophone n. (Historical) A device that transmitted sound on a beam of light. • photophone n. (Obsolete) A home phone with integral picture frame. • photophone n. (Dated) A stills-only cameraphone. Used to distinguish from video-capable camera cellphones and camera-less… |
| PHOTOPHORE | • photophore n. (Biology) A light-emitting organ, found in some fish and other marine animals. • photophore n. (Medicine) A form of endoscope using an electric light. • PHOTOPHORE n. a luminiferous organ. |
| PHOTOTROPE | • PHOTOTROPE n. a substance exhibiting phototropism, movement directed by light. |
| TOCOPHEROL | • tocopherol n. (Biochemistry) Any of several isomers of the principal component of vitamin E, each containing a chromanol… • TOCOPHEROL n. vitamin E, found in wheatgerm, egg yolk etc. |