TACIT HYPOTHECATION. In the civil law, a species of lien or mortgage which is created by operation of law without any express agreement of the parties. Mackeld. Rom. Law, § 343. In admiralty law,’ this term is sometimes applied to a maritime lien, which is not, strictly speaking, an hypothecation in the Roman sense of the term, though it resembles it. See The Nestor, 1 Sumn. 73, 18 Fed. Oas. 9.