Quick Definition
εὐθύτης, ητος, ἡ n.f. straightness, uprightness
Strong's Definition
rectitude
UBS Dictionary of the Greek New Testament
noun, f. | -ητος | εὐθύς
88.19 · Moral and Ethical Qualities and Related Behavior · Just, Righteous
righteousness, righteous, uprightness the quality of uprightness In a number of languages it makes no sense to speak of a ‘righteous scepter,’ and therefore this expression in HEB 1:8 may be better rendered as ‘you will rule righteously’ or ‘the way in which you rule is just.’
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
εὐθύτης, τητος, ἡ, (fr. the adj. εὐθύς), rectitude, uprightness: trop. ῥάβδος εὐθύτητος, an impartial and righteous government, Heb. i. 8 fr. Ps. xliv. (xlv.) 7.
Mounce Concise Greek Dictionary
εὐθύτης euthutēs 1x
righteousness, uprightness, equity, Heb. 1:8*
Abbott-Smith Greek Lexicon
εὐθύτης, -ητος, ἡ
(< εὐθύς), [in LXX chiefly for יֹשֶׁר, מִישׁוֹר and cognate forms ;]
uprightness: He 1:8 (LXX).†
Liddell-Scott-Jones — Greek-English Lexicon
εὐθύτης (euthutēs) — righteousness. εὐθύτης [ῠ], ητος, ἡ, (εὐθύς) straightness, opposed to καμπυλότης, [Refs 4th c.BC+]; opposed to περιφέρεια, [Refs]; εὐ. τριχῶν, opposed to οὐλότης, [Refs]; ἡ εὐ. τῆς τάσεως the direction.., [Refs 2nd c.AD+]
II. righteousness, [LXX]