PREFIXES. En-; for-; in- and un-Un- for modern in-; in- for un-. (Non- only occurs twice in all the plays of Shakespeare, and in V. and A. 521.)
Incharitable, infortunate, incertain, ingrateful, incivil, insubstantial.
Unpossible, unperfect, unprovident, unactive, unexpressive, unproper, unrespective, unviolable, unpartial, unfallible, undividable, unconstant, uncurable, uneffectual, unmeasurable, undisposed, unvincible (N. P. 181), unreconciliable (A. and C. v. 1. 47).We appear to have no definite rule of distinction even now, since we use ungrateful, ingratitude; unequal, inequality.1 Un- seems to have been preferred by Shakespeare before p and r, which do not allow in- to precede except in the form im-. In- also seems to have been in many cases retained from the Latin, as in the case of "ingratus," "infortunium," &c. As a general rule, we now use in- where we desire to make the negative a part of the word, and un- where the separation is maintained--"untrue," "infirm." Hence un- is always used with participles--"untamed," &c. Perhaps also un- is stronger than in-. "Unholy" means more than "not holy," almost "the reverse of holy." But in "in- attentive," "intemperate," in- has nearly the same meaning, "the reverse of."
Here "unseeming" means "the reverse of seeming" more than "not seeming" (like οὔ φημι): "in thus making us as though you would not confess."
“You wrong the reputation of your name
In so unseeming to confess receipt.