The kanji 減, at its core, represents the concept of "to decrease," "to reduce," "to lessen," or "to subtract." It implies a reduction in quantity, size, intensity, or value. The idea is to make something smaller or less. It's about taking away something that exists.

・On-yomi (音読み): ゲン ・Kun-yomi (訓読み): へ（る）, へ（らす）

⚫︎体重を減減らす Translation: To reduce one's weight. ⚫︎家賃が減減る Translation: The rent decreases. ⚫︎費用を減減らす Translation: To cut costs.

The kanji 減 is a phono-semantic compound (形声文字, けいせいもじ). The left side is 水（みず） "water," which is the semantic component, and the right side is 咸（かん）, the phonetic component indicating the pronunciation. The meaning of 水 here implies the concept of flowing away, or disappearing. The original meaning might have been related to the gradual decrease or lessening of something, like water receding. Over time, the meaning broadened to encompass a general decrease or reduction.