Sentence:  At the same time the multiple transvestitism involved - the fat man as girl and as baby , as coquette pretending to be a <WSD>baby</WSD> - touches for a moment horrifyingly upon the secret sources of a life like Jacoby 's , upon the sinister dreams which form the sources of any human life . 
Meaning of the word marked with <WSD> tags:  a very young child (birth to 1 year) who has not yet begun to walk or talk