Kontraux
Signifies opposition, both position (kontraux mia domo means "facing my house", not "beside my house") and also abstract, as in "battle against poverty", "guard against sickness". It can also be used as a prefi. The word legxo means "law", and kontrauxlegxa means "illegal".
Information provided by the Esperanto HyperCourse Maintainer as part of the Esperanto HyperCourse.