What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
Of, relating to, or designating the uppermost division of the Jurassic of Europe, in which Portland oolite occurs, sometimes regarded as a stage lying above the Kimmeridgian.
The Portlandian stage or series of rocks. Chiefly with the.
Mid 19th century; earliest use found in The North British Review. From the name of Portland + -ian, after Portland oolite.