Praecox is a Latin term meaning "very early". It is often used as a qualifying adjective in Latin binomials, and could mean "early flowering", "primitive", "premature" or "early onset" (in the case of medical conditions).
Plants
Agapanthus praecox, a South African bulbous plant Aira praecox, a European grass Allium praecox, a Californian onion Casearia praecox, a West Indian tree Chimonanthus praecox, wintersweet, a Chinese shrub Clematis 'Praecox', a flowering shrub cultivar Cytisus × praecox, a spring-flowering shrub Hydrangea paniculata 'Praecox', a flowering shrub cultivar Lindera praecox, an Asian shrub Medicago praecox, a Mediterranean plant in the pea family Pittocaulon praecox, a Mexican shrub in the daisy family Pleione praecox, an Asian orchid Rhododendron 'Praecox', a flowering shrub cultivar Roscoea praecox, a Chinese perennial in the ginger family Stachyurus praecox, a shrub from Japan Thymus praecox, a European thyme Weigela praecox, a shrub from Russia
Fungi Agrocybe praecox, a northern hemisphere mushroom Gymnopilus praecox, a North American mushroom
Animals Actebia praecox, the Portland moth Ceratotherium praecox, an extinct rhinoceros Denticetopsis praecox, a South American fish Deroceras praecox, an east European slug Iotabrycon praecox, an Ecuadorean fish Melanotaenia praecox, a rainbow fish from West Papua Mordacia praecox, a lamprey from Australia Thamnophilus praecox, the Cocha antshrike, a bird from Ecuador Persia praecox, a trilobite
Medical conditions Dementia praecox, a degenerative disease of late puberty and early adulthood Ejaculatio praecox, premature ejaculation in human males Lymphedema praecox, a swelling of the lymph nodes Pubertas praecox, premature puberty in humans