One can say something mixing words from two languages (say, English and
It depends on what you take ‘language’ to mean. I take it to mean, roughly, a set of rules for constructing meaningful sentences. These rules specify a list of words and ways of putting them together to form sentences. It specifies the meaning of each word and how to compute the meaning of sentences from the component words and the way they are put together. All typical human languages conform to the principles of what Noam Chomsky called ‘Universal Grammar.’ Universal Grammar is a set of principles for the construction of languages, which severely constrain the range of possible human languages. All normal human children are born with a representation of Universal Grammar encoded in their mind/brains and they (or their mind/brains) use this representation to construct a representation of a language that resembles those of the people around them. Each normal adult human has at least one language represented in their mind/brains. Each such language is unique to the individual, though it will be very similar to those of many other speakers. What we call ‘English’, ‘French’ etc. are just somewhat arbitrary groupings of individual languages. So if I say e.g. ‘Je voudrais a cup of tea’ I am using a sentence of my language, or one of my languages, and many others will be able to understand it because it is a sentence of their languages too. It is an unusual sentence in that French languages and English languages tend to use different vocabularies and grammatical principals. But it is not too hard to mix and match and draw on elements of both to construct a single meaningful sentence. Also it is not hard artificially to construct a new language with just one sentence in it. Thus: the language GL contains the one, syntactically-unstructured sentence: ‘Чайбудьласка,Дарлінг’ which, when uttered or written by speaker at a time, expresses the proposition that the speaker would like a cup of tea at that time.