a substance obtained by or used in a chemical process Farmers are being urged to reduce their use of chemicals and work with nature to combat pests. Word Origin late 16th cent.: from French chimique or modern Latin chimicus, chymicus, from medieval Latin alchymicus, from alchimia, from Arabic al-kīmiyā', from al
‘the’ + kīmiyā' (from Greek khēmia, khēmeia ‘art of transmuting metals’).Extra examples We don’t use many chemicals on our farm these days. chemicals discharged by industry into our lakes and rivers pollution from a big chemical plant Hormones are chemicals that are released in the body and control many important functions. This chemical is often used to make cleaning products.