a kind of long bacteria, one of which causes disease

bacteria

unclean metal (e.g. dust, mud), especially when it is where it is not wanted (e.g. on the skin, clothes, in buildings)

grime, impurity

a dirty mass; obscene language, pictures etc

dirt, pollution

(a coating of) dirt on the surface of something or on the body

dirt

any very small creature, especially one causing disease

bacteria