An old Portsmouth (Pompey) and westcountry descriptive or affectionate word, used as a generic term for a small child or baby.
A child of a young-enough age whereby all, even boys, would have been kept wearing dresses. (Until the 1930's in Portsmouth this was from birth to 6-9 years old).
Generic example: 'How's yer Bidger?' meaning 'How is your child? (or baby)'
In this sense, 'Bidger' is interchangeable with 'little one', the Pompey pronunciation being 'littl'in', as in ''ows littl'in' meaning 'How is your little one'.
The author's grandmother used this word regularly, she was Pompey born and bred, born in 1886. The word was used by her parents and grandparents, which illustrates that this is an old word, and the family roots are mixed Portsmouth and westcountry.
The word may be a derivation of the old Viking word 'bide' or 'byda' (both pronounced 'bidder'), meaning 'little' or 'small'. Viking words are found extensively in the westcountry, for example in the Cornish language.
Despite the initial definition in the urban dictionary, in the author's experience in Portsmouth this word was never in any way connected or associated with the 'gay' community. (Unless, perhaps, the person concerned was 'tiny'?)