Nouns

(n)appreciation, grasp, holdunderstanding of the nature or meaning or quality or magnitude of something“he has a good grasp of accounting practices”
(n)compass, range, reach, graspthe limit of capability“within the compass of education”
(n)grip, graspan intellectual hold or understanding“a good grip on French history”, “they kept a firm grip on the two top priorities”, “he was in the grip of a powerful emotion”, “a terrible power had her in its grasp”
(n)clasp, clench, clutch, clutches, grasp, grip, holdthe act of grasping“he released his clasp on my arm”, “he has a strong grip for an old man”, “she kept a firm hold on the railing”

Verbs

(v)grasp, hold onhold firmly
(v)grok, get the picture, comprehend, savvy, dig, grasp, compass, apprehendget the meaning of something“Do you comprehend the meaning of this letter?”