1
: a line at right angles to a goal line or end line and marking a side of a court or field of play for athletic games
2
a
: a line of goods sold in addition to one's principal line
b
: a business or activity pursued in addition to one's regular occupation
3
a
: the space immediately outside the lines along either side of an athletic field or court
b
: a sphere of little or no participation or activity
—usually plural
Cite this Entry
“Sideline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sideline. Accessed 5 Sep. 2026.
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