Definition of "insucking"

Yoritomo met their smiles and kowtowings and noisy insuckings of breath with an austere dignity that I took pains to imitate.

1910, Robert Ames Bennet, The Shogun's Daughter

Her initial response to this was a retropulsion or insucking of the tongue, so severe that speech was impossible, and she was in continual danger of swallowing her tongue.

1973, Oliver Sacks, Awakenings