Lexical Definition

‎ἄχρηστος‎ áchrēstos (akh'-race-tos) useless ^G:A
from ‎Α‎ (as a negative particle) and ‎χρηστός‎

unprofitable.

• inefficient, i.e. (by implication) detrimental

Abbott-Smith

ἄ-χρηστος, -ον, [in LXX: Ho 8:8 (חֵפֶץ אַיִן), Wi 2:11, Si 16:1, al.;]
useless, unserviceable: opp. to εὔχρηστος, Phm 11.†

Abbott-Smith References

Liddell-Scott-Jones

ἄχρηστος-τος, ον,

useless, unprofitable, μετάνοια[Refs 5th c.BC+]; χρεομένῳ ἄχρηστοςτα useless if you try to use them, [Refs 5th c.BC+]without effect, [Refs 5th c.BC+]; ἄ. τινι useless to a person, [Refs 5th c.BC+]; τῇ πόλει[Refs 5th c.BC+]

__2 ={ἀχρεῖος} (which it almost superseded in the Oratt. and later Greek), useless, do-nothing, [Refs 4th c.BC+]; ἄ. πολῖται[Refs 4th c.BC+]; σοφισταί probable reading in [Refs 5th c.BC+]; non-effective, unwarlike, Eun.Hist.p.239D.; so (with a pun—not having received an oracle) [Refs 2nd c.AD+]. adverb -τως, ἔχειν πρός τι[Refs 4th c.BC+]
__II unkind, cruel, θεοί[Refs 5th c.BC+]
__III active, making no use of, with dative, ξυνέσει τ᾽ ἄχρηστοςτον τῇ φύσει τε λείπεται[Refs 5th c.BC+]
__IV not used, i.e. new, ἱμάτια[Refs 2nd c.AD+]
__IV.2 obsolete, [Refs 5th c.BC+]
__IV.3 not to be used, unseemly, [Refs]