Thank You

On this post, we will look at the various ways of saying thank you in the Romance languages, in comparison to each other and Latin. Although this expression of gratitude has different origins in some of these languages, they all conserve, to some extent, the original Latin GRATIAS in the phrase meaning thanks to, which we will review at the end.

Portuguese
Obrigado
From the past participle of the verb obrigar; from the Latin OBLIGARE, originally meaning to bind, to tie around (cf. Latin LIGARE, to tie, to bind and OB, on account of, because of, a compound in many verbs) ; later, to oblige, to force. Obrigado then means (I am) obliged (to you). Traditionally, it agrees in gender and number with the speaker(s); so obrigado m. sing., obrigada f. sing., obrigados m. pl, obrigadas f. pl.; it is also used, however, as an interjection, without any agreement whatsoever, regardless of who says it (so a woman may say obrigado); this is not considered incorrect*. To thank (someone) would be ficar obrigado(a)(s) a alguém or agredecer a alguém; Thank you very much, muito obrigado(a)(s).

Spanish
Gracias
From the Latin GRATIAS, short for the idiom GRATIAS TIBI AGO, I lead my regards to you. Simpler than the Portuguese one, there is no agreement of any kind in Spanish for this expression. It can be used in the phrase dar las gracias a alguien, literally to give the thanks to someone. Like in Portuguese, the verb agradecer (a alguien) can also be used to mean to thank (someone). Muchas gracias would be thank you very much.

Catalan
Gràcies
Same Latin origin as explained for Spanish above. The cognate phrases for the same expressions are donar les gràcies a algú, to thank someone, expressed also by the verb agrair (a algú). Many thanks would then be Moltes gràcies.

Italian 
Grazie
Again, same origin as Catalan and Spanish above, but formed from the Latin nominative GRATIAE (instead of the accusative, as above, GRATIAS). Grazie mille (lit. one thousand thanks) is often used along with Molte grazie to express thank you very much. The verbs in Italian change a bit from we have just seen in the last two languages: ringraziare qualcuno or rendere grazie a qualcuno for to thank someone.

French
Merci
From the Latin MERCEDEM (accusative of MERCES), originally meaning pay, salary, or reward, later carrying the meaning of our English mercy or pity. Little remains of that connotation in modern French, with the word having become the interjection to express gratefulness*. Akin to the verb construction in Italian, remercier quelqu'un is used for to thank someone.

Romanian
Mulțumesc
Unlike all the other languages, this is not a noun or an adjective; it's a form of the verb mulțumi, to thank. According to DEX, this verb comes from the Romanian expression la mulți ani, used to wish someone a happy birthday, or a happy new year. Being that mulțumesc is a verb form, it must be conjugated, and so, a person, male or female, will say mulțumesc, but a group of people would say mulțumim. Often accompanied by the dative pronoun for the person(s) being thanked: îți mulțumesc, I thank you; vă mulțumim, we thank you all.
An invariable mersi is also used, coming directly from the French merci.


Now, let's analyze the expression thanks to in each language, along with the words for thank you as seen above, and compare their retention of Latin GRATIA. Even when the Latin GRATIAS to signal gratefulness has been displaced by other words in some of these languages, it is preserved in the phrase thanks to:

Latin	Portuguese	Spanish	Catalan	French	Italian	Romanian
GRATIAS	Obrigado	Gracias	Gràcies	Merci	Grazie	Mulțumesc
GRATIAS + Dative	Graças a	Gracias a	Gràcies a	Grâce à	Grazie a	Grație1 + Dative

Concentrating on the second phrase in the chart above, thanks to, we find GRATIA mostly in the plural within Romance, coming either from the Latin nominative (in Italian and Romanian) or the accusative (in the rest of the languages presented), being used as a preposition. Interestingly, in French, we find it in the singular, grâce (perhaps influenced by a related Latin expression GRATIĀ + genitive, with GRATIĀ in the ablative singular, meaning on the account of, for the sake of), although in modern French pronunciation, the plural would be indistinguishable from the singular, i.e. grâce vs. grâces, both /gʀɑs/. In Romance, GRATIAS is followed by  Latin A or the dative in Romanian, just like in Latin itself, in which it was likewise followed by the dative case (GRATIAS TIBI, [I] thank [especifically] you; with the fall of the declension system, in Vulgar Latin *GRATIA(S) A TE, cf. Pt. Graças a ti; Sp. Gracias a ti; Cat. Gràcies a tu; Fr. Grâce à toi; from *GRATIAE A TE, It. Grazie a te; and finally, with the dative, Rom. Grație ție).


¹Also used are mulțumită (+ dative), from the past participle of the verb mulțumi, to thank, as seen above; and datorită (+ dative), from the verb datori, variation of datora, itself formed from the noun dator*, meaning indebted (to) (ultimately derived from the Latin DEBITOR, debtor, one who owes).