| hard rays | Ray's of short wavelength and great penetrability. (05 Mar 2000) |
|---|---|
| hard science | A field of scientific study which involves precise measurements of observations and well-defined methods for obtaining and interpreting new knowledge. Chemistry and physics are definitely hard sciences, biology, geology, and astronomy also are usually thought of as hard sciences. Psychology, sociology, and anthropology are not, and are considered soft sciences. (09 Oct 1997) |
| hard soap | A soap made with olive oil, or some other suitable oil or fat, and sodium hydroxide; used as a detergent, and in the form of a suppository or soapsuds enema for constipation; used also as an excipient in pills. Synonym: Castile soap. (05 Mar 2000) |
| hard sore | The primary skin lesion of syphilis which begins at the site of infection after an interval of 10-30 days as a papule or red ulcerated skin lesion. (27 Sep 1997) |
| hard tarter | <dentistry> A calcium salt concretion which forms on your teeth. Calculus deposits form on the teeth in areas which you do not floss or brush. If these concretions are left to build up on the tooth enamel, they will irritate the gum tissue, push it away from the tooth and promote progressive bone loss. Eventually the teeth can loosen and fall out. These deposits can be removed by a dentist or a dental hygienist on an annual to biannual basis. (27 Sep 1997) |
| hard tissue | Tissue that has become mineralised, tissue having a firm intercellular substance, e.g., cartilage and bone. (05 Mar 2000) |
| hard tubercle | A tubercle lacking necrosis. (05 Mar 2000) |
| hard ulcer | <dermatology> The primary skin lesion of syphilis which begins at the site of infection after an interval of 10-30 days as a papule or red ulcerated skin lesion. (27 Sep 1997) |
| hard water | <chemistry> Hard water is water which contains minerals like calcium carbonate, magnesium carbonate, bicarbonates, sulphates, or chlorides, because it has been exposed to rocks or rocky soils. Hard water can corrode, discolour, or deposit its minerals, in and around materials such as water pipes. (09 Oct 1997) |