‘毒草’ literally means ‘poisonous grass’ or ‘poisonous plant’. It combines the character 毒 (dú), meaning ‘poison’ or ‘toxic’, and 草 (cǎo), meaning ‘grass’, ‘herb’, or more broadly ‘plant’. Though ‘草’ often refers to grasses, in compound words like this it commonly extends to non-woody vascular plants—including wild herbs, weeds, and flowering species that contain harmful alkaloids, glycosides, or other toxins.

The term is used in both scientific and everyday contexts: botanists and pharmacologists use it to classify hazardous flora, while in daily life it appears in safety warnings, gardening guides, and public health education—especially regarding accidental ingestion by children or pets. Some well-known examples include 颠茄 (deadly nightshade), 乌头 (aconite), and 夹竹桃 (oleander). Unlike the more technical term 有毒植物 (yǒu dú zhíwù), ‘毒草’ carries a slightly colloquial, sometimes even literary tone, and may evoke historical or metaphorical usage (e.g., in mid-20th-century political discourse), though its primary modern sense remains botanical and medical.