What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
Germinal; progenitive; prolific. Now rare.
Mid 19th century; earliest use found in Todd's Cyclopaedia of Anatomy and Physiology. From scientific Latin proliger (K. E. von Baer De ovi mammalium et hominis genesi 13, in discus proliger; from classical Latin prōlēs + -ger: see -gerous) + -ous.