bite, gnaw, chew, gear with, dash against
咬 centers on the action of teeth closing on something: biting, gnawing, or chewing. The extended senses of gears meshing or dashing against something come from the same idea of forceful, repeated contact.
咬 combines 口 (mouth) with 交, which likely contributes the sound and suggests the action of teeth meeting or crossing. The exact historical development is uncertain.
A mouth 口 beside 交, which looks like crossed lines, suggests teeth coming together to bite or gnaw.
For コウ, imagine a dog biting a bone with a loud 'koh!' sound: koh -> コウ, and the mouth 口 clamps down.
occlusion
bite wound; bite
malocclusion
bite wound; bite
occlusal force; biting force; bite force
articulator
masticating surface; occlusal surface
lockjaw; trismus
masseter muscle
attrition; occlusal wear
attrition; occlusal wear
cusp (of a tooth)
open bite; apertognathia
ratbite disease