辣 means 'bitter'

It's logical that 甘 and 蜜 represent sweetness in food, whereas 辛 and 辣 set the mouth on fire in relation to spicy dishes. But all four kanji also have figurative applications; 甘 and 蜜 appear in terms for "honeyed words" meant to "sweet-talk" people, whereas 辛 and 辣 combine in 辛辣 (bitter (criticism)). Moreover, 甘 and 辛 unexpectedly act as antonyms in words for "lenient" versus "harsh" and in terms about preferences for sweets versus alcohol. The two kanji (both radicals, incidentally!) even team up in an expression for "tasting the sweetness and bitterness of life."