pseudosibling

Etymology

From pseudo- + sibling.

pseudosibling means One who is not a sibling but has a relationship of that kind. Lexicurio rates it Sui generis — a strength score of 85 out of 100.

noun

One who is not a sibling but has a relationship of that kind.“[…] the girls were older than average when they entered the family and thus did not develop the usual pseudosibling relationship […]”