Early 17th century; earliest use found in Thomas Overbury (d. 1613), courtier and author. Probably irregularly from multure + -ary, after e.g. sumptuary.
Definition of mulctuary in US English:
mulctuary
adjective
rare
That punishes by a fine.
Origin
Early 17th century; earliest use found in Thomas Overbury (d. 1613), courtier and author. Probably irregularly from multure + -ary, after e.g. sumptuary.