AD- n.
As a prefix ad- assumes the forms ac-, af-, ag-, al-, an-, ap-, ar-, as-, at-, assimilating the d with the first letter of the word to which ad- is prefixed. It remains unchanged before vowels, and before d, h, j, m, v. Examples: adduce, adhere, adjacent, admit, advent, accord, affect, aggregate, allude, annex, appear,…
DEAD-EYE n.
A round, flattish, wooden block, encircled by a rope, or an iron band, and pierced with three holes to receive the lanyard; -- used to extend the shrouds and stays, and for other purposes. Called also deadman's eye. Totten.