From Middle English plege, from Anglo-Norman plege, from Old French plege (Modern French pleige) from Medieval Latin plevium, plebium, from Medieval Latin plebire "to pledge", from Frankish *plegan (“to pledge, support, guarantee”), from Proto-Germanic *plegō (“responsibility, habit”), from Proto-Indo-European *dlegh-. Akin to Old High German pflegan (“to take care of, be accustomed to”), Old Saxon plegan (“to vouch for”), Old English plēon (“to risk, endanger”). More at plight.
pledge (third-person singular simple present pledges, present participle pledging, simple past and past participle pledged)
- To make a solemn promise (to do something).
- To deposit something as a security; to pawn.
- (transitive) To give assurance of friendship by the act of drinking; to drink to one's health.
- 1773, Oliver Goldsmith, She Stoops to Conquer
- HARDCASTLE [Taking the cup.] I hope you'll find it to your mind. I have prepared it with my own hands, and I believe you'll own the ingredients are tolerable. Will you be so good as to pledge me, sir? Here, Mr. Marlow, here is to our better acquaintance. [Drinks.]
- 1852, Matthew Arnold, Tristram and Iseult
- Reach me my golden cup that stands by thee,
- And pledge me in it first for courtesy.
to make a solemn promise
- Arabic: تَعَهدَ (ar)
- Catalan: prometre (ca)
- Cantonese: 誓 (sai6)
- Gan: please add this translation if you can
- Hakka: please add this translation if you can
- Mandarin: 發誓 (cmn), 发誓 (cmn) (fāshì)
- Min Dong: please add this translation if you can
- Min Nan: please add this translation if you can
- Finnish: luvata (fi), sitoutua (fi)
- French: promettre (fr)
- German: zusichern (de), versprechen (de)
- Hebrew: please add this translation if you can
- Icelandic: please add this translation if you can
- Indonesian: please add this translation if you can
- Italian: promettere (it), impegnarsi (it)
- Japanese: 公約する (ja) (kōyaku suru)
- Korean: please add this translation if you can
- Latin: spondere (la), vovere (la)
- Malay: ikrar (ms)
- Polish: obiecać (pl)
- Portuguese: prometer (pt)
- Romanian: promite (ro), garanta (ro)
- Russian: обещать (ru) (obeščatʹ), заверять (ru) (zaverjatʹ), клясться (ru) (kljastʹsja)
- Serbo-Croatian: zaloga, zavet, zavjet, obećanje, prisega
- Slovak: please add this translation if you can
- Slovene: zapriseči, zavezati se, zaobljubiti se
- Spanish: prometer (es), jurar (es)
- Thai: please add this translation if you can
- Vietnamese: cam kết (vi), thề (vi)
to deposit something as a security; to pawn
pledge (plural pledges)
- A solemn promise to do something.
- A person who has taken a pledge of allegiance to a college fraternity, but not yet formally approved.
- A security to guarantee payment of a debt.
- A drinking toast.
- (the pledge): A promise to abstain from drinking alcohol.
Derived terms 
person who has taken a pledge of allegiance to a fraternity
promise to abstain from drinking alcohol