Pyrethrum /pī-rēˈthrəm, or (esp US) pī-rethˈrəm or (rare) pi-rethˈrəm/

1. A former genus of composite plants, including feverfew, now considered as belonging to the genus Chrysanthemum
2. (without cap) a name still applied to various garden flowers, esp varieties of Chrysanthemum coccineum
3. (without cap) insect-powder made from the flower-heads of various species of pyrethrum
4. (without cap) in pharmacy, the root of pellitory of Spain (see pellitory²)

pyrēthˈrin (or (esp US) /-rethˈ/) noun

Either of two insecticidal oily esters prepared from pyrethrum flowers

• casting-weight
• casting-weights
• cast in one's lot with
• cast in someone's teeth
• cast iron
• cast-iron
• cast irons
• castle
• castle-building
• castled
• castle-guard
• castle-guards
• castle nut
• castle nuts
• chorus master
• chorus masters
• chose
• chose in action
• chose jugée
• chosen
• choses
• chota
• chota hazri
• chota peg
• chota pegs