bite, chew
噉 centers on using the mouth to grip and grind: biting and chewing. The two given meanings are closely related actions of the mouth.
噉 combines 口 (mouth) with 敢, which likely contributes the sound タン. The character is used for biting and chewing, actions done with the mouth.
The mouth 口 on the left and 敢 on the right suggest a bold mouth action: biting down and chewing firmly.
For タン, imagine a tongue biting and chewing: tongue -> タン, and the mouth 口 does the work.