孑然 is a literary word meaning 'alone, solitary'. You'll almost always encounter it in the fixed phrase 孑然一身 (jiérán yìshēn, 'to be all alone in the world'). Unlike common words like 独自, 孑然 carries a strong literary and poetic tone, used in writing or formal speech to emphasize a lonely, self-sufficient state. It does not function as a verb despite the POS label — it's used as an adverb or adjective, typically modifying a verb or a noun like 一生, 独立, or 无依. Be careful not to use it in everyday conversation; it sounds archaic.