What does ipsilateral mean?
Ipsilateral is a technical adjective meaning “on the same side.” It is used especially in anatomy, medicine, and neuroscience to describe a body structure, neurological event, or other phenomenon lying on the same side of the body's midline or a specified reference point as another structure or site. For example, damage to the left motor cortex may produce weakness in the ipsilateral, or left, limbs, while a lesion affecting one side of the spinal cord can affect motor pathways described as ipsilateral or contralateral depending on the pathway involved. The term is especially useful when discussing hemispheres, visual fields, nerves, muscles, lesions, and surgical procedures. It contrasts with “contralateral,” meaning on the opposite side. Although ipsilateral can be replaced informally by “on the same side,” the formal term allows medical and scientific writing to be concise and unambiguous. It belongs primarily to specialist and academic registers rather than everyday conversation.
adjectiveLocated on or occurring on the same side of a body, organ, or other reference axis. In anatomy and neuroscience, it describes structures or events on the same side of the body's midline or relative to a specified site.
- Located on or occurring on the same side of a body, organ, midline, or other reference point.
"The lesion caused weakness in the ipsilateral arm and leg."
"The surgeon preserved the ipsilateral blood vessels during the procedure."
"Stimulation of the ipsilateral hemisphere produced movement on the same side of the body."
Ipsilateral and contralateral are mirror-image specialists: one points to the same side, the other to the opposite side.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ipsilateral come from?
Ipsilateral was formed in English from the combining form ipsi-, derived from Latin ipse, meaning “same,” and lateral, which comes from Latin lateralis, meaning “of or relating to a side.” The formation parallels related terms such as bilateral and contralateral. Its principal meaning has long been established in anatomical and neurological usage.
Related word forms
How ipsilateral is actually used
A technical term used chiefly in anatomy, medicine, neuroscience, and related biological sciences. It is more precise than the informal phrase “on the same side,” especially when a midline, organ, lesion, or other reference point is understood.
Easily confused with ipsilateral
Ipsilateral means on the same side as a reference point, whereas contralateral means on the opposite side.