1609 J. Dowland tr. A. Ornithoparchus Micrologus 58 As oft as two alterable Notes are placed between two imperfectible [L. imperfectibiles] Notes without a Pricke of Division, the Second is always altered.

1968 in C. A. Miller tr. F. Gaffurius Practica Musicae ii. x. 92 Since three hooked minims do not have a ternary division when divided by a minim, we do not propose any imperfectible note smaller than a minim, which is the last note in ternary division among modern writers.

1991 B. J. Blackburn in B. J. Blackburn et al. Corr. Renaissance Musicians ii. a. vii. 271 According to the rules of imperfection, notes that cannot imperfect the neighbouring note of greater value must be transferred to the next imperfectible note.

1616 T. Willis Search of Causes vi. 15 The last perfection of all things is spirit, and the last cleansing is by fire, which is the violence of the spirit consuming all matter imperfectible.

1797 New Ann. Reg. 1796 Domest. Lit. 199/1 Animals are imperfectible, but men are perfectible without end.

1826 Republican 16 June 762 These [sc. Colonies] must circulate the sap or laws of the parent trunk, and nothing but the same wild and imperfectible fruit can be produced.

1870 F. W. Farrar Families of Speech iv. 156 Many of them apparently as imperfectible as the Ainos of Jesso or the Veddahs of Ceylon.

1949 Illustr. London News 14 May 650/3 We live, it should be remembered, in an imperfect and imperfectible world.

2010 Internat. Stud. Rev. 12 283 Whether people are fallen or ultimately alone, ethical and successful action remains vexing, imperfectible, and necessary.

1800 H. Summersett Leopold Warndorf II. 27 The manifest imperfectibility of human nature.

1971 Nature 31 Dec. 523/1 The same principle of imperfectibility applies to all sex chromosome mechanisms.

2013 R. J. Merrett D. Defoe: Contrarian i. 3 Truth about the human condition is reached only through acknowledgment of its imperfectibility.