In addition to ample doses of repetition, anaphora, and allusions to Sherlock Holmes and Napoleon, this comic poem uses the following poetic devices.
Rhyming couplets convey a pleasing, sing-song sense of rhythm that helps structure the poem, such as "paw" and "law" and "despair" and "there." Eliot also uses alliteration to create rhythm. Alliteration puts words beginning with the same consonant in close proximity: an example would be the repeated "f" sounds in "footprints," "found," and "file" in stanza five.
The speaker adopts a hyperbolic voice, which, along with the sing-song rhymes, gives the poem its tone of light-hearted humor. Hyperbole or exaggeration, is critical to humor, and this speaker lays it on thickly, crediting to the ever-missing Macavity increasingly larger and more absurd crimes. Macavity moves from being responsible for missing milk to being accused of stealing important Foreign Office treaties. The absurdity is underscored as the absence of evidence of Macavity's presence at these crime scenes becomes evidence of his crime.
Macavity's name is a pun on a cavity (a hole) and being missing. It reflects the cat's mysterious absences.
Eliot also uses imagery, which is description employing any of the five senses of sight, sound, touch, taste, or smell in the poem. For instance, we are offered a visual description of Macavity:
a ginger cat, he’s very tall and thin;
You would know him if you saw him, for his eyes are sunken in.
This description morphs into personification, for Macavity comes to look more like a human being than a cat:
His brow is deeply lined with thought, his head is highly domed
Eliot's poetic devices successfully entertain us in this comic romp.