Noun
A frontal or brow band; a fillet or band worn on the forehead.
A frown (likened to a frontlet).
The margin of the head, behind the bill of birds, often bearing rigid bristles.
Source: Webster's dictionaryAccording to the memo, General Steakley "briefed the committee on a sensitive DOD project known as FRONTLET 615," which is identified in a handwritten note on the original memorandum as "submarine within U.A.R. waters." Source: Internet