rudiment

noun

• 1 (the rudiments of) the first principles of (a subject):she taught the girls the rudiments of reading and writing
• an elementary or primitive form of (something):the rudiments of a hot-water system

• 2 Biology an undeveloped or immature part or organ, especially a structure in an embryo or larva which will develop into an organ, limb, etc.:the fetal lung rudiment

• 3 Music a basic pattern used by drummers, such as the roll, the flam, and the paradiddle.