[Noun] This is the shortened way of writing Formula 1. Formula 1 is a category of racing cars.
First filial generation.
Offspring resulting from the mating of a purebred (straight-bred) bull to purebred (straight-bred) females of another breed.
Offspring resulting from the mating of a purebred (straightbred) bull to purebred females of another breed. 
Breeders use this term and it refers to the first generation offspring, from two plants that have been bred. The F1 may have desired qualities of either or both parents.
See neuromodulin.
The first filial generation, or the first-generation offspring of a given mating.
The first (filial) generation of a cross. Usually the progeny from an F1 cross will be phenotypically fairly uniform. 
, F2, F3, etc. filial generation, with the generation specified by the subscript numeral.
The F1 is an accurate Australian blowback operated, selective fire sub-machine-gun produced around 1960 as a replacement for the earlier Owen, and incorporating components from the L1A1 rifle. The F1 takes a 9 mm Parabellum round from a 34-round curved box mounted over the receiver. It has a cyclic rate of 600-640 rounds-per-minute and an effective...
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The first generation of offspring resulting in the mating of a purebred bull and a cow of another breed.
Abbreviation for Formula One.