[furst-dey, -dey] /ˈfɜrstˌdeɪ, -ˈdeɪ/
a cover marked so as to indicate that it was mailed on the first day of issue of the stamp it bears and from one of the cities at which the stamp was issued on that day.
[furst-di-gree] /ˈfɜrst dɪˈgri/ adjective 1. of or relating to the lowest or first in a series. 2. of or relating to the highest or most serious in a series.
- First-degree murder
noun, Law. 1. See under (def 1). [mur-der] /ˈmɜr dər/ noun 1. Law. the killing of another human being under conditions specifically covered in law. In the U.S., special statutory definitions include murder committed with malice aforethought, characterized by deliberation or premeditation or occurring during the commission of another serious crime, as robbery or arson […]
- First-degree burn
noun, Pathology. 1. See under 1 (def 37). [burn] /bɜrn/ verb (used without object), burned or burnt, burning. 1. to undergo rapid combustion or consume fuel in such a way as to give off heat, gases, and, usually, light; be on fire: The fire burned in the grate. 2. (of a fireplace, furnace, etc.) to […]
noun, Mathematics. 1. the derivative of a function: Velocity is the first derivative of distance with respect to time.