rancid breath – Rancid refers to a matter which is disagreeable or offensive. Hence, the lady’s voice when she speaks to the poet is immensely unpleasant.
squelching tar – Squelch is a verb which means to press or strike with a crushing force. Hence, the expression which is used here is that of a large amount of tar, a dark-coloured product which is obtained after the distillation of wood or coal, describing the poet’s complexion.
spectroscopic flight of fancy – Spectroscopy is a word which originated from the topic of the dispersion of light into seven different colours. Hence, the word describes the dispersed flow of thoughts of the lady after talking to the poet. Her fancies of a dark man gaining wings and attaining high levels of interpretation when she had to accept the fact that she did not know much more than the person on the other side.
rearing on the thunderclap – Thunderclap resembles the unexpected occurrence of thunder, as in loudness.
brunette – Brunette means dark skin, dark hair and darkish or olive skin.
peroxide blonde – This term refers to the unnaturally or harshly bleached palm and the sole of feet rather than the fair complexion. Peroxide is basically a chemical used as a bleaching agent.
clinical assent – The lady’s voice in the poem sounded clinical when assenting to the revelation of the poet. It means the concerned voice, according to an actual and vivid observation of the poet, giving into the situation after a lot of inspection and thoughts.
raven black – Raven black is a metaphorical expression which explains the intensity of the black colour. The Raven is a large, dark-coloured bird of the crow family. This metaphor is used to describe people who are dark-skinned.