a silvery carangid fish of the genus Selene, of the Atlantic Ocean, having a compressed body and eyes placed high on the truncated forehead.
Origin of lookdown
1880–85, Americanism; noun use of verb phrase look down
the appearance of paper when inspected under reflected light.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Online Etymology Dictionary, © 2010 Douglas Harper