as its written in the poem 'the duck and the kangaroo'.i guess its in the 2nd paragraph.its the same word pronounced as rheumatism.you might be knowing what rheumatism means.its written in the order to make the 2 sentences rhyming.Authoprs and Poets have the right to coin new words and phrases.This is one such word coined by the poet to rhyme the paragraph and let the sounding move smoothly.
