This is the 7431st most frequent Japanese word.
侮っ
"侮っ" means "to belittle" or "to disdain."
Here, "侮っ" (as part of "侮って") is used to convey the meaning of looking down or underestimating someone in a cautionary statement.
彼を侮ってはいけません。
You must not underestimate him.
In this sentence, "侮っ" (as part of "侮る") refers to treating something (nature) lightly or not giving it the respect and attention it deserves, stressing the importance of recognition.
我々は自然を侮るべきではありません。
We should not underestimate nature.
Here, "侮っ" (as part of "侮る") emphasizes the unwise judgment in looking down on or misjudging the opponent's strength, representing reflection on the action.