Somewhat peaked or pointed; characterized by peaks.
Mid 18th century; earliest use found in William Ellis (c1700–1758), agriculturist and writer. From peak + -ish.
Somewhat sickly; pinched, unhealthy.
Mid 19th century; earliest use found in Benjamin Smart (d. 1872), elocutionist and grammarian. Probably alteration of peaky, with suffix substitution.
Of, relating to, or characteristic of the Peak District in Derbyshire.
In early use apparently sometimes more generally: rough, remote, wild.
Late 16th century; earliest use found in William Warner (d. 1609), poet and lawyer. From Peak + -ish.