A primitive root; to refuse, forbid, dissuade, or neutralize -- break, disallow, discourage, make of none effect.
Englishman's Concordance
1) to hinder, hold back, forbid, disallow, restrain, frustrate 1a) (Qal) to hinder, hold back 1b) (Hiphil) 1b1) to restrain, forbid, frustrate 1b2) to restrain, make averse, discourage Part of Speech: verb A Related Word by BDB/Strong’s Number: a primitive root Same Word by TWOT Number: 1317
Brown-Driver-Briggs
[נוא] verbhinder, restrain, frustrate (Arabic () (or ) rise with difficulty, rise against one (Frey), III. contend with, Lane2861); —
1restrain, forbid (performance of vow), followed by accusative of person Numbers 30:6 (twice in verse); Numbers 30:9; Numbers 30:12; frustrate (device of people), subject ׳י, followed by accusative of thing, Psalm 33:10 ("" הֵפִיר); refusePsalm 141:5 ((text dubious see Che).
2restrain, make averse the heart (accusative) Numbers 32:7 (followed by מֵעֲבֹר), Numbers 32:9 (followed by לְבִלְתִּיבֿאֹ).
Englishman's Concordance (References)
Strong's Hebrew: 5106. נוּא (nu) — 8 Occurrences
Numbers 30:5 HEB: וְאִם־ הֵנִ֨יא אָבִ֣יהָ אֹתָהּ֮ NAS: her father should forbid her on the day KJV: But if her father disallow her in the day INT: if forbid her father the day
Numbers 30:5 HEB:לָ֔הּ כִּי־ הֵנִ֥יא אָבִ֖יהָ אֹתָֽהּ׃ NAS: her father had forbidden her. KJV: her, because her father disallowed her. INT: will forgive her because had forbidden her father
Numbers 30:8 HEB:שְׁמֹ֣עַ אִישָׁהּ֮ יָנִ֣יא אוֹתָהּ֒ וְהֵפֵ֗ר NAS: hears [of it], he forbids her, then he shall annul KJV: But if her husband disallowed her on the day INT: hears her husband forbids shall annul her vow
Numbers 30:11 HEB:לָ֔הּ לֹ֥א הֵנִ֖יא אֹתָ֑הּ וְקָ֙מוּ֙ NAS: [it], but said nothing to her [and] did not forbid her, then all KJV: [it], and held his peace at her, [and] disallowed her not: then all her vows INT: said not forbid shall stand all
Numbers 32:7 HEB:[תְנוּאוּן כ] (תְנִיא֔וּן ק) אֶת־ NAS: Now why are you discouraging the sons KJV:And wherefore discourage ye the heart INT: now why break the heart the sons
Numbers 32:9 HEB:אֶת־ הָאָ֔רֶץ וַיָּנִ֕יאוּ אֶת־ לֵ֖ב NAS: the land, they discouraged the sons KJV: the land, they discouraged the heart INT: and saw the land discouraged the heart the sons
Psalm 33:10 HEB:עֲצַת־ גּוֹיִ֑ם הֵ֝נִ֗יא מַחְשְׁב֥וֹת עַמִּֽים׃ NAS: of the nations; He frustrates the plans KJV: of the people of none effect. INT: the counsel of the nations frustrates the plans of the peoples
Psalm 141:5 HEB:רֹ֭אשׁ אַל־ יָנִ֣י רֹאשִׁ֑י כִּי־ NAS: Do not let my head refuse it, For still KJV: oil, [which] shall not break my head: INT: the head nay refuse my head For
) 
(or 
) rise with difficulty, rise against one (Frey), III. contend with, Lane2861); —