herbicide
n. C / U B2 Upper Intermediate US //ˈɝbɪˌsaɪd// UK //hˈɜːbɪsˌaɪd// her·bi·cide
n. a chemical used to kill unwanted plants, like weeds. Farmers and gardeners use it to keep their crops or lawns clean.
n. a chemical substance used to kill or inhibit the growth of unwanted plants. Often used in agricultural or horticultural contexts to manage weeds.
The farmer applied an herbicide to the fields to kill the weeds.
Before planting the new vegetable garden, the gardener used an herbicide to clear the soil of invasive grasses.
While effective at controlling broadleaf weeds, the specific herbicide must be applied carefully to avoid damaging the surrounding crops or contaminating the local water supply.
From herb + -icide.