Such jaw-gripping tenacity is used to describe the force that the ending ‘-cious’ adds to words, as in the word ‘tenacious’. Thoreau observes and analyses language as incisively as he observes and analyses nature.
‘… the greediness, as it were, and tenacity of purpose with which the husbandman and householder is required to be a seller and not a buyer, – with mastiff-like tenacity, – these lipped words which, like the lips of moose and browsing creatures, which greedily collect what the jaw holds; as in the word “tenacious” the first half represents the kind of jaw which holds, the last the lips which collect. It an only be pronounced by a certain opening and protruding of the lips; so “avaricious.”‘
Source: Henry David Thoreau, The Journal 1837-1861, Damion Searls (ed.), preface by John R. Stilgoe (New York: New York Review Books, 2009), p. 72