Boot-lick is a slang term that refers to a person who is overly submissive to someone in a position of authority. There are various synonyms for this word, including sycophant, toady, lackey, flatterer, yes-man, and brown-noser. Sycophant implies a person who flatters and ingratiates themselves in order to gain advantage. Toady is another term used for a person who fawns over their superiors, often in hopes of gaining favor. Lackey refers to a servant or someone who performs menial tasks for their boss. Flatterer and yes-man both indicate a person who agrees with their superiors regardless of their own beliefs. Brown-noser is a cruder term that implies someone who flatters excessively to gain personal advantages.