Diakonissa is a Greek title of honor that is used to refer to a deacon's

Deacon

Deacon is a ministry in the Christian Church that is generally associated with service of some kind, but which varies among theological and denominational traditions...

 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.

Diakonissa was also the term used in the ancient Church for the order of deaconess

Deaconess

Deaconess is a non-clerical order in some Christian denominations which sees to the care of women in the community. That word comes from a Greek word diakonos as well as deacon, which means a servant or helper and occurs frequently in the Christian New Testament of the Bible. Deaconesses trace...

, a non-clerical

Clergy

Clergy is the generic term used to describe the formal religious leadership within a given religion. A clergyman, churchman or cleric is a member of the clergy, especially one who is a priest, preacher, pastor, or other religious professional....

 order which saw to the care of women in the community.

Other languages

In Arabic, a deacon's wife is called Shamassy (derived from Shamas, Arabic for "deacon"). Romanian uses a derivative from the Greek term, Diaconiţă, as does Serbian, Djakonitsa . Other Slavic traditions generally use the same word for a deacon's wife that is used for a priest's wife

Presbytera

Presbytera is a Greek title of honor that is used to refer to a priest's wife. It is derived from presbyteros—the Greek word for priest...

: Matushka (Russian), Panimatushka (Ukrainian), etc.