LIVER
Pun Play: If you’re having trouble getting the answer, just FILTER your knees and pray!

My Gameplay: DONUT, SWEAR, RIVER, LIVER
The etymology on liver was quite an interesting read. If you’d like the cliff notes version:
-The LIVER was once believed to be the blood-producing organ of the body.
-It’s the largest organ in the human boday
-It’s about the size of a football.
You’re welcome. On to tomorrow!