The Portuguese language has proved of particular interest to linguists because of the complexity of its phonetic structure. There are 9 oral vowel sounds, 5 nasal vowels, 2 semi-vowels (j and w), many diphthongs (oral and nasal), and even triphthongs. There is a great difference in pronunciation between closed and open a, e, and o. The nasalization is indicated by a tilde placed over the vowel, or by an m or n placed after it. Phonetic analysis of Portuguese reveals 25 separate consonantal sounds, which have almost the same value as in other Romance languages, with some variation from region to region. The most important variations are that rr is generally alveolar in Portugal and frequently uvular or guttural in Brazil, and that sounds corresponding to English [ch] and [dj] do not exist in Portugal but are found in Brazil represented by ti and di. Lh corresponds to Spanish ll and Italian gl. Nh corresponds to Spanish ñ and Italian gn. Ch and j are pronounced as in French. The dental character of the consonants d, t, n, and l is more pronounced in Portuguese than in English, because in Portuguese pronunciation the tongue tends to touch the base of the upper teeth. The linking together in spoken Portuguese of syntactically related words in a sentence accounts for the variation in the sound of a number of consonants. This phenomenon is particularly evident in the case of the sibilant consonants s and z.
One of the most distinctive features of Portuguese, compared with other Romance languages, is the loss of the so-called intervocalic l and n. Thus, quais represents the Latin quales and pessoa the Latin persona. The Portuguese forms of the definite article o, a ("the") are due to the intervocalic position of the l in such syntactical combinations as de-lo and de-la ("of the"), from which have resulted the contracted forms do and da, and by a redivision of the compound, d'o and d'a. A word ending in l in the singular loses the l in the plural due to its intervocalic position. Thus, the singular of "sun" is sol, but the plural is sóis.
Portuguese retains many grammatical forms no longer found in other members
of the Romance language group. The future subjunctive and future perfect
subjunctive, for example, remain in use. As in old forms of Spanish, the
endings of the future and the conditional in modern Portuguese may be detached
from the stem to permit the interpolation of the object pronoun. Portuguese
is the only Romance language with a personal or inflected infinitive. For
example, partir ("to depart") may be conjugated partir
eu, "for me to depart" or "that I may depart." In addition to the
compound pluperfect, Portuguese has also a simple one developed from the
Latin plusquamperfect; thus the pluperfect of amara means
"I had loved" in addition to the conventional "I would love". Portuguese
closely parallels Spanish in its grammar. A great number of nouns have
the distinctive endings of a for the feminine form and o for the masculine
form, corresponding to Latin nouns of the first and second declensions,
respectively. The sign of the plural in Portuguese is regularly s.