uncount

From un- +‎ count.

uncount (third-person singular simple present uncounts, present participle uncounting, simple past and past participle uncounted)

1. (transitive, intransitive) To deduct from a count; discount or subtract.
   • 2017, Eugenia Cheng, Beyond Infinity:

     Children accomplish learning how to count, and then almost immediately they have to learn how to 'uncount', that is, subtract.

   • 2019, Sue Pope, Pablo Mayorga, Enriching Mathematics in the Primary Curriculum, page 84:

     The jar rocks and falls, allowing the mice to 'uncount' themselves from the jar. The large mouse turns out to be a rock and the snake is left hungry.

From un- +‎ count.

uncount (not comparable)

1. (linguistics, grammar) Uncountable.
   • 2014, James Lambert, “Diachronic stability in Indian English lexis”, in World Englishes, page 118:

     For example, the term abuse would require at least one definition for the uncount usage ‘invective, insulting language’, and another for the count usage ‘an item of invective, an insult’.