淡水【たんすい】
fresh water (i.e. not salt water)
濃淡【のうたん】
light and shade, shade (of colour, color), depth (of flavor), complexity, strength and weakness (of flavor)
冷淡【れいたん】
cool, indifferent, apathetic, half-hearted, cold, cold-hearted, heartless, unkind
淡い【あわい】
light, faint, pale, fleeting