It is not easy to tease out any central meaning to this poem, nor did Eliot intend it to be. This is part of his deliberate strategy as a Modernist poet, to make his poem rather difficult to understand; he provides no clear context or information to what exactly is going on. What we are presented with is a rather confusing insight into the mind of the speaker, the Prufrock of the title. The poem is rather difficult and obscure as it aims to follow the exact train of his thoughts, which are meandering and disconnected, a series of fragments rather than a coherent whole.
However, looking at the poem closely, and deducing as much as we can from the text we are given, we can piece together a picture of an extremely lonely, dissatisfied man, trapped in an stultifying modern urban environment, bored almost to death by ‘tedious’ everyday routines of taking tea, making superficial social visits, walking along drab, endless streets, and enduring evenings so dull they are compared, most strikingly, to 'a patient etherised upon a table’, and choked with fog. He feels completely out of it; he frets about his appearance, what he should wear, about the ladies who perceive him with a critical eye, and he worries about growing old. He appears lonely in the extreme: even although he is addressing someone else, this person is never identified, and it might well be that he is simply talking to himself. In fact, he feels himself to be so insignificant that he remarks that he should just have been ‘a pair of ragged claws/ scuttling across the floor of silent seas.’ He imagines himself, then, as a very lowly creature, rather than as a human being, supposedly the highest and wisest of all the animals. Prufrock doesn’t feel like this, however.
In short, Prufrock feels that he and his society are, essentially, worthless. Therefore, we might rather paradoxically conclude that the central meaning or message of the poem is the lack of meaning in modern urban life - certainly for individuals like Prufrock. As in the work of many modern writers, in this poem we get a picture of an individual who is almost wholly alienated from the modern urban environment in which he lives, which appears bleak, boring, and threateningly impersonal. However, this lack of meaning is treated with irony rather than wholesale despair; Prufrock knows that he cuts a sorry figure and mocks himself and his own pretensions.
Basically, the poem is about a man who feels like a failure in love and life. He measures out life by the coffee spoons (his life is a huge rut) and worries that even the siren (women who lure men to their watery deaths) will reject him. This is a man with the worst self-esteem possible. Ironically, the central meaning is that Prufrock feels he has no meaning.