cognate

adj. from the same source, of the same parentage; similar in nature or form

n. relative, kin, person or thing that is related to another

In linguistics, cognates are words that have a common origin. They may occur within a language, such as shirt and skirt as two English words descended from the Proto-Indo-European word *sker-, meaning "to cut". They may also occur across languages, e.g. night and German Nacht as descendants of Proto-Indo-European *nokt-, "night".
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Noun
1. one related by blood or origin; especially on sharing an ancestor with another
(synonym) blood relation, blood relative, sib
(hypernym) relative, relation
2. a word is cognate with another if both derive from the same word in an ancestral language
(synonym) cognate word
(hypernym) word
Adjective
1. related in nature; "connate qualities"
(synonym) connate
(similar) related, related to
2. having the same ancestral language; "cognate languages"
(similar) related, related to
(classification) linguistics
3. related by blood
(synonym) akin(p), blood-related, consanguine, consanguineous, kin(p)
(similar) related

n. sister in law, sister of the husband, sister of the wife

n. brother in law, brother of the husband, brother of the wife

(n.)
One who is related to another on the female side.
  

(n.)
One of a number of things allied in origin or nature; as, certain letters are cognates.
  

(a.)
Of the same or a similar nature; of the same family; proceeding from the same stock or root; allied; kindred; as, a cognate language.
  

(a.)
Allied by blood; kindred by birth; specifically (Law), related on the mother's side.