Jimjams - Slang. extreme nervousness; jitters. Origin: Jimjams is a gradational compound based on the word jam meaning "to press, squeeze, or fill tightly." The sense “nervous jitters” entered English in the 1800s.
Ossify - to become rigid or inflexible in habits, attitudes, opinions, etc.: a young man who began to ossify right after college. Origin Ossify stems from the Latin word for "bone," os. It entered English in the