Despise someone and your scorn for them will turn into full-on contempt.

侮蔑 is a formal word, mainly used in writing, that describes words, tone, or behavior which is contemptuous and demeaning. For example, derogatory expressions can be called 侮蔑的な表現, and speech that openly belittles someone may be described as 侮蔑を込めた言い方.

This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.