Emily Dickinson Lexicon

CAS'U-AL, a. [cazh'ual; Fr. casuel; Sp. and Port. casual; It. casuale; from L. casus, a fall. See Case and Accident.]

1. Falling; happening or coming to pass, without design in the person or persons affected, and without being foreseen, or expected; accidental; fortuitous; coming by chance; as, the parties had a casual encounter.
2. Occasional; coming at certain times, without regularity, in distinction from stated, or regular; as, casual expenses.
3. Taking place, or beginning to exist without an efficient intelligent cause, and without design. Atheists assert that the existence of things is casual. – Dwight.