Initialism of relative humidity. / (music, knitting) Initialism of right hand. / Initialism of review hearing. / (US, army, aviation) Initialism of reconnaissance helicopter.

(medicine) Abbreviation of Rhesus factor. / (medicine) Abbreviation of Rhesus.

Initialism of right-hand side. / (construction) Initialism of rectangular hollow section.

Initialism of Royal Horticultural Society.

plural of RH

Pertaining to the Rh-null syndrome, or blood produced by the syndrome.

Ellipsis of Rh-null blood.; a blood type, in which red blood cells are completely lacking in all antigens of the Rh-blood-typing system (Rh factors), a system of 61 antigen types.

Abbreviation of Rhesus factor.

Abbreviation of Rhesus positive.

Abbreviation of Rhesus negative.