Diakonissa is a Greek title of honor that is used to refer to a deacon's wife. It is derived from diakonos—the Greek word for deacon (literally, "server"). There does not currently seem to be any standard English equivalent, so most English-speaking Orthodox Christians will use the title most common in the old country churches from which their local family or parish finds its origin.
In Arabic, a deacon's wife is called Shamassy (derived from Shamas, Arabic for "deacon"). The Slavic tradition generally uses the same word for deacon's wife that is used for a priest's wife: Matushka (Russian), Papadija (Serbian), Panimatushka (Ukrainian), etc.