A quickie today as I’m squeezing the Daily Hanzi in at lunch time. I see 禁 all the time on signs in the park. I suspected it had something to do with prohibitions (what else do wordy signs in parks tell you other than “no campfires, no skateboarding, no unleashed dogs,” etc.)
The radical 示 (shì) is an uncommon one, and according to zhongwen.com has an unusual history. It means something like “the revealed truths of gods” and carries a vague connotation of “demonstrate, show, protest.” It’s topped in 禁 by two 木 (mù: “wood, tree”) characters.
Altogether this character emits a potent bronze age miasma: forbidden forests? Augured taboos? Wooden idols?