Other forms: rethinking, rethought, rethinks
To rethink is to think about something again from the start. Rethink the plan, a complete rethink, time for a rethink.
It implies starting over rather than adjusting, which is what separates it from reconsider — reconsidering may leave the answer the same and rethinking rarely does. As a noun, a rethink is the process: the policy needs a rethink. Note the past tense rethought; and that a rethink is a face-saving way of announcing a reversal.
1verbrethinkTo think about something again from the start.
“The plan failed so badly that we need to rethink the whole thing.”
2nounreconsiderationSuch a reconsideration.
“Falling sales forced a rethink of the company's whole strategy.”
rethink is a fresh consideration.
Middle English
thinken
English
think
English, today
rethink
From re- + think. think comes from Middle English thinken. From Middle English thinken, thynken, thenken, thenchen, from Old English þenċan, from Proto-West Germanic þankijan, from Proto-Germanic þankijaną (“to think”), from Proto-Indo-European teng- (“to think, feel, know”). Cognate with Scots think, thynk (“to think”), frr teenk, taanke, tanke, tånke (“to think”), stq toanke (“to think”), West Frisian tinke (“to think”), Dutch denken, dinken (“to think”), Afrikaans dink (“to think”), Low German denken, dinken (“to think”), German denken (“to think”), Danish tænke (“to think”), Swedish tänka (“to think”), Norwegian Bokmål tenke (“to think”), Norwegian Nynorsk tenkja (“to think”), Icelandic þekkja (“to know, recognise, identify, perceive”), Gothic þagkjan (“to think”), Latin tongeō (“know”).
Etymology from Wiktionary, CC BY-SA