Adjective : The word has no assignable meaning in our language. ,This work is assignable to a 12th-century poet.    From Dictionary.com. 

Artists and scientists own unassignable primary copyrights and patents on their creations, inventions and discoveries.    From Wordnik.com.  [The Evil of Lesser Idiots: Another Inconvenient Truth] Reference

Gains of large size, it is proposed, may be free of tax if paid to the government, to be held without inter est and in completely unassignable form, to be taxed in the year of withdrawal at the taxpayer's will.    From Wordnik.com.  [Tax! Tax! Tax!—The Canadian Tax Scene] Reference

People moved everywhere, yet there was only a mild hum of unassignable noise, a blending of typeout machines, human voices, and a steady tremor that seemed everywhere and nowhere, that came from the rock itself.    From Wordnik.com.  [Across The Sea Of Suns]

Thirdly I would like to see individual performers granted a ‘moral right’ in their performance that is unassignable and shall last for 95 years; this will be in order to prevent objectionable uses of their material.    From Wordnik.com.  [B2fxxx] Reference

If earnings remain unassignable they are placed in a "suspense" file; however, investigation continues.    From Wordnik.com.  [Ventura County Star Stories] Reference

This kind of elimination, in which we do not eliminate any one assignable cause, but the multitude of floating unassignable ones, may be termed the.    From Wordnik.com.  [A System Of Logic, Ratiocinative And Inductive] Reference

The phenomenon of which he sought for the one cause has oftenest no cause at all, and when it has, depends (as far as hitherto ascertained) on an unassignable variety of distinct causes.    From Wordnik.com.  [A System Of Logic, Ratiocinative And Inductive] Reference

As our mental fields succeed one another, each has its centre of interest, around which the objects of which we are less and less attentively conscious fade to a margin so faint that its limits are unassignable.    From Wordnik.com.  [The Varieties of Religious Experience] Reference

5 an unassignable certificate of such payment.    From Wordnik.com.  [(House of Representatives, No. 379.) : an act to levy additional taxes for the year eighteen hundred and sixty-five for the support of the government,] Reference

If in looking he makes a mistake of half the thickness of one of these threads, the observation is good for nothing; judge what his uneasiness must be; at the critical moment, a puff of wind occasioning a vibration in the artificial light adapted to his telescope, the threads become almost invisible; the star itself, whose rays reach the eye through atmospheric strata of various density, temperature, and refrangibility, will appear to oscillate so much as to render the true position of it almost unassignable; at the very moment when extremely good definition of the object becomes indispensable to insure correctness of measures, all becomes confused, either because the eye-piece gets steamed with vapour, or that the vicinity of the very cold metal occasions an abundant secretion of tears in the eye applied to the telescope; the poor observer is then exposed to the alternative of abandoning to some other more fortunate person than himself, the ascertaining a phenomenon that will not recu.    From Wordnik.com.  [Biographies of Distinguished Scientific Men] Reference