E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Clause.
Letter-clause, a close letter, sealed with the royal signet or privyseal, in opposition to letters-patent, which are left open, the seal being attached simply as a legal form. (“Clause,” Latin clausus, shut, closed. “Patent,” Latin patens, open.)
li clausi).
