危 is a bound form (b.f.) that cannot stand alone as an independent word in modern Chinese. It appears as the first or second element in compounds such as 危险 (wēixiǎn, dangerous), 危机 (wēijī, crisis), and 危害 (wēihài, to harm). In classical Chinese it can mean 'high, steep' (e.g., 危楼 'a tall building') or 'upright, proper,' but these senses are rare in everyday speech. When you see 危 in a compound word, the core meaning is usually related to danger or jeopardy.