恐 means 'fear'

Do these kanji frighten you? After all, they overlap considerably. You could render おそれる (to fear) with all four characters, and people often use 恐 and 怖 interchangeably to convey myriad fears (e.g., of business risks). But this bundle makes important distinctions. You'll see that 恐 connects to respect (e.g., for Nature's power), politeness, financial crises, and uncertainty about the future. The essay on 怖 explores uniquely Japanese phobias. Meanwhile, 虞 expresses concern and caution in the face of threats. And 惧 mainly relates to endangered entities (species, occupations, or railways) and the fear of extinction.