I. ri-ˈzi-jə-wəl, -jəl; -ˈzij-wəl noun
Etymology: Latin residuum residue
Date: 1557
1. : remainder , residuum : as
a. : the difference between results obtained by observation and by computation from a formula or between the mean of several observations and any one of them
b. : a residual product or substance
c. : an internal aftereffect of experience or activity that influences later behavior ; especially : a disability remaining from a disease or operation
2. : a payment (as to an actor or writer) for each rerun after an initial showing (as of a TV show)
II. adjective
Date: 1570
1. : of, relating to, or constituting a residue
2. : leaving a residue that remains effective for some time
a residual pesticide
• re·sid·u·al·ly adverb