I will arrive in an hour: without crasis because when the feminine noun is changed to a masculine noun ("Chegarei daqui a um minuto" I will arrive in a minute), there is no "ao" (as "um/uma", indefinite articles, appear instead of "o/a"). The grave accent is never used before masculine words (nouns, pronouns, etc.); verbs; personal pronouns; numerals, plural nouns without the use of the feminine plural definite article as ("the"); city names that do not use a feminine article; the word casa ("house") if it has the meaning of one's own home; the word terra ("earth") when it has the meaning of soil; and indefinite, personal, relative or demonstrative pronouns (except the third person and aquele(s) or aquela(s)); between identical nouns such as dia a dia "day by day", "everyday", "daily life", gota a gota "dropwise", "drip", and cara a cara "face to face"; and after prepositions. Here are exceptions: É preciso declarar guerra à guerra! (It is necessary to declare war on war!) É preciso dar mais vida à vida. (It is necessary to give more life to life.) Crasis also occurs between the preposition de and the definite articles. de o → do de a → da de os → dos de as → das Optional crasis The grave accent is optional in the following cases: Before a female's first name Refiro-me [à/a] Fernanda. (I am referring to Fernanda.) Before a feminine possessive pronoun Dirija-se [à/a] sua fazenda. (Go to your [own] farm.) After the preposition até Dirija-se até [à/a] porta. (Go by that door.) Eu fui até [à/a] França de carro. (I traveled to France by car.) Spanish In Spanish, crasis occurs between the prepositions a or de and the masculine definite article el. a el → al de el → del See also Assimilation (linguistics) Clitic Contraction (grammar) Elision Liaison (French) Sandhi Notes and references Notes References External links Greek Grammar Phonology Greek language Portuguese language es:Crasis