proreption, n.

  The action of creeping forward; a slow advance.

Etymology:  < classical Latin prōrept-, past participial stem of prōrēpere to creep forward ( < prō- pro- prefix1 + rēpere to creep: see repent adj.2) + -ion suffix1.

1656   T. Blount Glossographia,   Prorepsion, a creeping forward, a stealing forward by little and little, a growing, spreading, or coming forth.

1658   J. Robinson Endoxa x. 55   The slow proreption of every Sidus, out of his proper Sign.

1682   R. Harrison Strange Relation suddain & violent Tempest 4   You might have beheld an unusual Proreption of Animalcles out of the Bowels of the Earth, hunting and searching about for Food.