To indent negatively, bring towards the margin.(verb)
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Use "outdent" in a sentence
"Tumblr's streamlined editor lacks some of the editing tools found in other blogging services, such as buttons for paragraph indent and "outdent" and a full-screen editing option, and the relatively small text entry field doesn't encourage you to write dissertations."
"Here, paragraphs are formatted with a style that produces an "outdent"."
"· Code commenting, auto-indent and outdent, block selection, incremental search, reflow paragraph, join lines, enter next character as raw literal, repeat next keystroke and clean line endings on "save"."