Is math a language? Is "language" a comprehensive description of mathematics? Maybe this is just a trivial description... or possibly there something about mathematics that is missed by describing it so... Certainly math is far more restricted than ordinary languages, but is math itself a proper language?
As a basis for what a constitutes a language, I refer to John Searle's article, "What Is Language?" Also, my thinking about math is informed by Wittgenstein's "Foundations Of Mathematics" and Russell's "Introduction To Mathematical Philosophy".
Obviously mathematics are not a language in the sense of an ordinary or commonly spoken and written language (whether colloquial, vernacular or something more formal). Inasmuch as language is a means of communication, however, it seems like "a language" is an accurate description of the abstract and formal means of dialogue and expressing ideas through intentionalistic utterance.
The standard textbook accounts of language say that specific languages such as French or German consist of three components: a phonological component that determines how words and sentences are pronounced, a syntactical component that determines the arrangement of words and morphemes in sentences, and a semantic component that assigns a meaning or interpretation to words and sentences. More sophisticated accounts add that there must also be a pragmatic component that is not a component of specific languages; rather, it sets certain constraints on the use of language and is not internal to specific languages in the way that the syntax of French is internal to French and the syntax of German is internal to German. ... The relation of syntax to semantics is however crucial. Syntax organizes semantics according to three principles: discreteness, compositionality and generativity. Discreteness is that feature by which syntactical elements retain their identity under the various syntactical operations. ... Compositionality is both a syntactic and a semantic property. Syntactically, a complex element such as a sentence is built up out of simple elements, words and morphemes, according to the formation rules of the language. Semantically, the meaning of the whole sentence is determined by the meanings of the simple elements together with the syntactical structure of the sentence. ... Generativity, as I am using the term, implies that the syntactical operations of the language allow the speakers to generate an indefinite number of new sentences. There is, strictly speaking, no upper limit to the number of sentences in any natural human language.
Though he notes that this is an incomplete picture of what constitutes a language, I think mathematics meet these criteria of phonology, syntax, semantics, as well discreteness, compositionality and generativity. Also, the deontological considerations he advances when considering the question "what is language?" I think are also met by mathematics (when you say "2+2=4" and mean it, you are committed to the utterance.)
Philosophy is written in this grand book, which stands continually open before our eyes (I say the 'Universe'), but can not be understood without first learning to comprehend the language and know the characters as it is written. It is written in mathematical language, and its characters are triangles, circles and other geometric figures, without which it is impossible to humanly understand a word; without these one is wandering in a dark labyrinth.
...I don't speak Italian, but in this translation "mathematical" is adjectival, possibly suggesting that mathematics are not necessarily a language, but sufficiently an aspect of ("what can be done with"?) language. Other translations say "the language of mathematics" and perhaps this is merely poetic license upon the translators part. For what it is worth, Galileo's "Egli è scritto in lingua matematica" from The Assayer is translated by Google Translate as the adjectival form. Not that interpreting Galileo is the final word on answering the question, but as a possible counter-example demonstrating that mathematics is instead a formal aspect or sub-set of the human capacity for language.
Considering the answer here to the question "what is a language?" perhaps the mathematics lack "biplanarità"? (For what does three refer to except for the taxonomy of counting and measuring?)
Is math a language?