noun Date: 1910 a slow baseball pitch that moves erratically and unpredictably and that is thrown with little spin by gripping the ball with the knuckles or the tips of the fingers pressed against the top, ~er noun
KNUCKLEBALL
Meaning of KNUCKLEBALL in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012