'Instillment' definitions:

Definition of 'instillment'

(from WordNet)
noun
The introduction of a liquid (by pouring or injection) drop by drop [syn: instillation, instillment, instilment]

Definition of 'Instillment'

From: GCIDE
  • Instillment \In*still"ment\, n. The act of instilling; also, that which is instilled. [Written also instilment.] [1913 Webster]