In·ter·stice n.; pl. Interstices
1. That which intervenes between one thing and another; especially, a space between things closely set, or between the parts which compose a body; a narrow chink; a crack; a crevice; a hole; an interval; as, the interstices of a wall.
2. An interval of time; specifically R. C. Ch., in the plural, the intervals which the canon law requires between the reception of the various degrees of orders.
Nonobservance of the interstices . . . is a sin. --Addis & Arnold.