Single

BILL, SINGLE, contracts. A writing by which one person or more, promises to another or others, to pay him or them a sum of money at a time therein specified, without any condition. It is usually under seal; and when so, it is sometimes, if not commonly, called a bill obligatory. (q. v.) 2 S. & R. 115.
     2. It differs from a promissory note in this, that the latter is always payable to order; and from a bond, because that instrument has always a condition attached to it, on the performance of which it is satisfied. 5 Com. Dig. 194; 7 Com. 357.

SINGLE. By itself, unconnected.
     2. A single bill is one without any condition, and does not depend upon any future event to give it validity. Single is also applied to an unmarried person; as, A B, single woman. Vide Simplex.