interstice

noun

1. 1

   A small opening or space between objects, especially adjacent objects or objects set closely together, as between cords in a rope or components of a multiconductor electrical cable or between atoms in a crystal.

2. 2

   A fragment of space.

3. 3

   An interval of time required by the Roman Catholic Church between the attainment of different degrees of an order.

4. 4

   (by extension) A small interval of time free to be spent on activities other than one's primary goal.