: a median line
especially
: the median line or median plane of the body or some part of the body
Examples of midline in a Sentence
Recent Examples on the Web
The stomach is located on the left side of the midline, so this position encourages food to pass more easily from the small intestine to the large intestine, which may help remedy or prevent an upset stomach.
—
Caitlin Carlson, SELF, 13 Feb. 2026
The pectoralis major runs from the collarbone and breastbone to the upper arm and is responsible for bringing the arms forward, drawing them toward the body’s midline and rotating them inward.
—Daryl Austin, USA Today, 1 Feb. 2026
In a small clinical trial in New York, pediatric oncologists harnessed the technology to temporarily—but repeatedly—open the blood-brain barrier in three children with a rare type of brain cancer called diffuse midline glioma.
—IEEE Spectrum, 19 Nov. 2025
China has also ramped up military pressure on the island, including near-daily flights across the midline of the Taiwan Strait and large-scale exercises simulating a blockade.
—Micah McCartney, MSNBC Newsweek, 5 Nov. 2025
See All Example Sentences for midline
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Caitlin Carlson, SELF, 13 Feb. 2026
The pectoralis major runs from the collarbone and breastbone to the upper arm and is responsible for bringing the arms forward, drawing them toward the body’s midline and rotating them inward.
—Daryl Austin, USA Today, 1 Feb. 2026
In a small clinical trial in New York, pediatric oncologists harnessed the technology to temporarily—but repeatedly—open the blood-brain barrier in three children with a rare type of brain cancer called diffuse midline glioma.
—IEEE Spectrum, 19 Nov. 2025
China has also ramped up military pressure on the island, including near-daily flights across the midline of the Taiwan Strait and large-scale exercises simulating a blockade.
—Micah McCartney, MSNBC Newsweek, 5 Nov. 2025
See All Example Sentences for midline
Cite this Entry
“Midline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/midline. Accessed 27 Feb. 2026.
Copy CitationKids Definition
midline
noun
mid·line
ˈmid-ˌlīn 
: a line through the middle of something
especially
: a line through a body or one of its parts that lies in a plane dividing it into halves that are mirror images of each other
Medical Definition
midline
noun
mid·line
ˈmid-ˌlīn, ˌmid-ˈlīn
: a median line
especially
: the median line or median plane of the body or some part of the body
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