• Bengali Word কষ ১ English definition (noun) 1 astringent juice of some plants or fruits: আমের কষ, গাবের কষ, কলাগাছের কষ. 2 stain caused by this juice: কষ লাগা. 3 tannic acid or tannin obtained from the bark of oak trees, and used in the manufacture of ink and in converting raw hides into leather.