irreptitiously

English

irreptitiously (comparative more irreptitiously, superlative most irreptitiously)

In an irreptitious manner.
- 1972, Augustus De Morgan, A Budget of Paradoxes Reprinted, with the Author's Additions, from the Athenaeum Augustus De Morgan, page 255:
  A quadrant is a curvilinear angle traversing round and at an equal distance from a given point, called a centre, no two points in the curve being at the same angle, but irreptitiously graduating from 90 to 60.