half sister
noun
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half sister
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half-sister
half-sisternounthe daughter of either of one's parents by another partner
half sister
Americannoun
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half sisters
plural
half-sister
British
noun
Usage
What does half sister mean? A half sister is a sister who is related to her sibling(s) through only one parent. This typically means that they share only one biological parent (not both). For example, when a person’s parent has a daughter with another partner (who is not the person’s parent), the daughter is considered the person’s half sister. The term half brother is used in the same way. Half-sibling is a gender-neutral way of saying the same thing. In contrast, the words stepsister, stepbrother, and stepsibling refer to those who have a sibling relationship (often based on the remarriage of their parents to other partners) but who do not share a biological parent. The word half in half sister and its related terms only refers to the biological relationship. Half sisters may have close relationships with their siblings, and many people simply call their half sister their sister. Modifiers such as maternal and paternal are sometimes used to specify which biological parent the siblings have in common. Example: Over the holidays, I got together with my maternal half sister and my paternal half brother and we had a great time.
Other Word Forms
Noun Inflected Forms
Etymology
Origin of half sister
Middle English word dating back to 1150–1200
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
When she opened her results and saw the mind-boggling truth that her twin was her half sister, Lavinia was distraught - and furious.
From BBC ● May 2, 2026
Ms. Kuehn met her father’s half sister, Ruth, only once, in 1987.
From The Wall Street Journal ● Dec. 4, 2025
Meghan is largely estranged from her half sister and their father, Thomas Markle.
From New York Times ● Mar. 12, 2024
Breasia was the half sister of Dinkins’ son, and investigators have said both children were staying the night with him at the apartment where he was living with a girlfriend.
From Seattle Times ● Aug. 10, 2023
According to family accounts and traditions, Sally also resembled her late half sister, Martha Jefferson.
From "In the Shadow of Liberty" by Kenneth C. Davis
The irony is that Sally was also Martha’s half-sister — the product of John Wayles’ relations with an enslaved woman — making her biological kin to the Monticello Association members, too.
From Salon ● Jul. 27, 2026
Not long afterward, Truelove traveled to New York City, where his half-sister said he spent time in multiple shelters and psychiatric facilities.
From Los Angeles Times ● Jul. 24, 2026
The couple lived in the block of flats with the boy's siblings - his 12-year-old sister and 10-year-old half-sister.
From BBC ● Apr. 10, 2026
The baby’s half-sister would be easier for the older couple to take care of.
From Salon ● Mar. 24, 2026
Only a month before, my ancient half-sister, who was twelve years older than me, had actually had appendicitis, and for several days before her operation I was able to observe her behaviour at close quarters.
From "Boy: Tales of a Childhood" by Roald Dahl
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
