From Middle English ensuren, from Anglo-Norman enseurer, from Old French seur.

• (RP) IPA: /ɪnˈʃʊə/, /ɪnˈʃɔː/
• (America) IPA: /ɪnˈʃʊɹ/, /ɪnˈʃɝ/

ensure (ensures, present participle ensuring; simple past and past participle ensured)

1. (transitive) To make a pledge to (someone); to promise, guarantee (someone of something); to assure. [14th]
   • 1485, Sir Thomas Malory, “[https://quod.lib.umich.edu/c/cme/MaloryWks2/1:18.8?rgn=div2;view=fulltext xvj]”, in Le Morte Darthur, book XVI:

     Thenne he cryed hym mercy and sayd Faire knyght for goddes loue slee me not / and I shall ensure the neuer werre ageynst thy lady / but be alwey toward her / Thenne Bors lete hym be

     (please add an English translation of this quotation)

2. (intransitive) To make sure or certain of something (usually some future event or condition). [from 18th c.]

   I use an alarm clock to ensure that I get up on time.

• insure
• assure
• inshore

• French: assurer, garantir, assurer
• German: sicherstellen, gewährleisten
• Italian: garantire, assicurare, fare in modo che
• Portuguese: garantir, assegurar
• Russian: удостове́риться
• Spanish: asegurar (pronominal), garantizar