Absurdity
As an example of the Theater of the Absurd, the overarching theme of the play is the revelation of the absurdity of life. This absurdity is reflected in a clock that strikes the hour of 17 and the breakdown of communication through the failure of language to make sense of the world around the characters. As the play wears on, the absurd quality of language devolves into a state of decay. Decay of meaning is a primal element in the Theater of the Absurd and the breaking down of language as the essential tool of communication reaches a point at which it becomes pretty much as effective as gibberish. Perhaps the singular defining aspect absurdity is that the play has nothing whatever to do with a bald prima donna.
The Tragedy of Language
Although the breakdown in language produces some very funny scenes, the play is referred to as tragedy of language. The tragedy is expressed as the play trek through the collapse of meaning in words from conversation that has no frame of reference through to a complete breakdown of any possible sense of communicative ability with characters spouting non-sequiturs void of even the most intangible of context. The tragedy here being the ignoble death of language with its tragic flaw being an inability to withstand assaults on its purpose
Isolation
Two characters who are married greet each other as strangers. Because of the breakdown of communication, when they meet at a party they need to engage in discourse with each other for some time before realizing that they are actually man and wife. This theme relates to the absurdity of modern life as well as the tragic implications of language first in the concept of strangers living together and then as a result of the time it takes for language to make clear their relationship to each other. The isolation and alienation these themes create within this relationship is also an essential and recurring component of the Theater of the Absurd.