Definition of "spongy"

Though no man lesser fears the Greeks than IAs far as toucheth my particular,Yet, dread Priam,There is no lady of more softer bowels,More spongy to suck in the sense of fear,More ready to cry out 'Who knows what follows?'Than Hector is:

c. 1602, William Shakespeare, “The Tragedie of Troylus and Cressida”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene ii]

[…] there were times when she would lie looking at her, with such a still, watchful, almost dangerous expression, that Helen would sigh, and change her place, as persons do whose breath some cunning orator had been sucking out of them with his spongy eloquence, so that, when he stops, they must get some air and stir about, or they feel as if they should be half-smothered and palsied.

1861, Oliver Wendell Holmes, chapter 28, in Elsie Venner‎, volume 2, Boston: Ticknor & Fields, page 246

It was easy to realise, too, the need for the overall 40 m.p.h. speed limit; apart from the spongy nature of much of the track bed, the [West Highland] line suffered considerably in the Arctic conditions of last winter, from which it has not yet fully recovered.

1964 January, Cecil J. Allen, “Locomotive Running Past and Present”, in Modern Railways, page 52

Thy banks with pioned and twilled brims,Which spongy April at thy hest betrims,

1610–1611 (date written), William Shakespeare, “The Tempest”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act IV, scene i]

Her who still weepes with spungie eyes,And her who is dry corke, and never cries;I can love her, and her, and you and you,I can love any, so she be not true.

1633, John Donne, “The Indifferent”, in Poems‎, London: John Marriot, page 200

[…] I was quite tired, and very glad, when we saw Yarmouth. It looked rather spongy and soppy, I thought, as I carried my eye over the great dull waste that lay across the river […]

1849 May – 1850 November, Charles Dickens, chapter 3, in The Personal History of David Copperfield, London: Bradbury & Evans, […], published 1850

It rains […] most of the fall and winter and much of the spring. It’s a spongy sky you’ll be wearing on your head.

1961, Bernard Malamud, A New Life‎, Penguin, published 1968, page 21