Figure of speech. Lenehan's transformation of the newsboys'
"footsteps" into "feetstoops" is consistent with other verbal
tricks that he performs in Aeolus, and with the entire
chapter's manipulations of language, but it cannot really be
characterized as a rhetorical device. It is perhaps best
described as a kind of anagram.
An anagram
(AN-uh-gram, from Greek
ana- = anew, backwards +
gramma
= letter) rearranges the letters of a word or phrase to make a
new word or phrase, ideally one which somehow comments on the
original. A quick search of internet sites will turn up dozens
of good examples: "dirty room" for "dormitory," "elegant man"
for "a gentleman," "Old West action" for "Clint Eastwood," and
"I'll make a wise phrase" for "William Shakespeare."
Lenehan's witticism does not quite play by the rules, since it
adds an extra "e," but both
Gilbert and Seidman identify
it as an anagram. It might alternatively be classed as
metathesis,
like "Clamn dever," but metathesis produces only variant
spellings of a word or phrase, not two different meanings, and
"feetstoops" arguably does produce an entirely new word. Seidman
finds a second instance of anagram later in
Aeolus, when
Lenehan wishes for "
a fresh of breath air," but this is
surely wrong, as no transposition of letters is involved.
Instead Lenehan has transposed entire words––performing
metathesis on a bigger scale, as it were.
If Joyce did intend "feetstoops" as a kind of anagram, he
was expanding his category of verbal constructs beyond the
lexicon of the ancient rhetoricians. Some French writer coined
the term anagramme in the 16th century. The OED
records its earliest English usage in George Puttenham's The
Arte of English Poesie (1589): "Of the Anagrame, or
poesie transposed." In The Silent Woman (1616), Ben
Jonson made a more descriptive reference to the device: "Who
will...make anagrammes of our names."