Language is a method of communication. It is used to transport information from one individual's brain to another brain. I'm not entirely sure about it, but I think every language which is wide-spread might be complete in a sense that once you know every word of the language you will be able to convey any concept or idea. In fact, even a tiny subset of natural languages might be enough to transport those ideas.
Basic components of a complete language
A complete language is always specific for the species for which it is used as one fundamental part is to describe sensory inputs. For example, bees can see other parts of the spectrum. They might describe flowers very differently from us. Some of the sensory words are:
- pain
- bright, dark, red, blue, round, rectangular, straight, curved
- sweet, bitter
- smokey, stinking
- hard / soft, warm / cold, rough
Another fundamental part of a complete language are relationships:
- Spatial: A is over / below / right of B
- Temporal: A is before / after B
- Structural: A is part of B; A is a type of B
- Comparing: A is smaller than B; A is better than B; A is higher than B
Thinking about this, there seem to be many conceptual words which cannot be explained with the ones given before:
- Language, knowledge, idea, wisdom, time, space
Other components of natural languages
Natural languages are much more than complete languages. They have words to define new words. Many words can be completely described with other words, but it is cumbersome to use many sentences instead of a single word.
Also, there are synonyms, filling words, words and grammar which helps to distinguish other words and make sure the other one does not misunderstand you.
Conclusions
There are two important conclusions from these thoughts:
First, the purpose of language is to convey ideas. This means on the one hand that you should use language like others do most of the time. On the other hand, there are some circumstances where you might want to ignore the "official" writing (e.g. in German "das Kalman-Filter" would be correct, but most people would intuitively say "der Kalman-Filter" - going with the intuitive version is fine here).
Second, it might be possible to define a minimal complete language to describe the world.