熱する
ねっする · nessuru · JLPT N2 · verb-suru
to heat
🔥 熱 (netsu, heat) + する (suru, to do) = do heat = to heat
熱 (netsu) means heat or fever, and する (suru) means to do. Joined, they give 'do heat', which is the verb to heat. The same pattern appears in 勉強する (study) and 運転する (drive).