line has 67 distinct synonyms spread across 19 of its 36 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a mark that is long relative to its width
“He drew a line on the chart”
a formation of people or things one behind another
“the line stretched clear around the corner”
a length (straight or curved) without breadth or thickness; the trace of a moving point
text consisting of a row of words written across a page or computer screen
“the letter consisted of three short lines”
a single frequency (or very narrow band) of radiation in a spectrum
a fortified position (especially one marking the most forward position of troops)
“they attacked the enemy's line”
a course of reasoning aimed at demonstrating a truth or falsehood; the methodical process of logical reasoning
“I can't follow your line of reasoning”
a conductor for transmitting electrical or optical signals or electric power
a spatial location defined by a real or imaginary unidimensional extent
a slight depression or fold in the smoothness of a surface
“his face has many lines”
the road consisting of railroad track and roadbed
a telephone connection
acting in conformity
“in line with”
the principal activity in your life that you do to earn money
“he's not in my line of business”
in games or sports; a mark indicating positions or bounds of the playing area
(often plural) a means of communication or access
“it must go through official channels”
a particular kind of product or merchandise
“a nice line of shoes”
a commercial organization serving as a common carrier
space for one line of print (one column wide and 1/14 inch deep) used to measure advertising
the maximum credit that a customer is allowed
a succession of notes forming a distinctive sequence
“she was humming an air from Beethoven”
persuasive but insincere talk that is usually intended to deceive or impress
“`let me show you my etchings' is a rather worn line”
a short personal letter
“drop me a line when you get there”
a conceptual separation or distinction
“there is a narrow line between sanity and insanity”
mechanical system in a factory whereby an article is conveyed through sites at which successive operations are performed on it
cover the interior of
“line the gloves”
Synonyms, antonyms and the broader and narrower relations for line come from Princeton University’s WordNet. Full sources and licences.
mark with lines
“sorrow had lined his face”
reinforce with fabric
“lined books are more enduring”