Genealogy kinship terminology has changed throughout history. Kinship terms may not mean what you think they mean. Genealogy research requires a strong understand of subtle and nuanced historical differences in language, customs, and habits. Genealogy Trek's summary of abbreviations may also be useful

Prior to about 1800, the terms in-law, cousin, grandchildren and orphan were used differently than they are used today.

In-law referred to a legal relationship and could mean step-son or step-daughter or half-brother or half-sister.

Cousin implied a genealogical relationship and generally meant a nephew or a niece.

Grandchildren included grandchildren and great grandchildren.

Orphan was any child whose father was deceased, even if the mother was still living.