From an unused root meaning to extend; properly, extent (of time); but used only adverbially (especially with other particle prefixes), when (either relative or interrogative) -- long, when.
H4970. mathay
מָתַי43 interrogative adverb when? (Arabic ; Assyrian mati: in Late Hebrew and Aramaic with the interrogative אֵימָת אֵימָתִי, אַי,, ), in OT only of future time:
a. alone, Genesis 30:30 לביתי אנכי גם אעשׂה מָתַי when shall I also do, etc.? Amos 8:5; Psalm 41:6; 42:3; 94:8; 101:2; 119:82; 119:84; Proverbs 6:9; b 23:35; Job 7:4 אָקוּם מָתַי, Nehemiah 2:6.
b. לְמָתַי against when? Exodus 8:5 אַעְתִּיר לְךָ לְמָתַי.
c. עַדמָֿתַי until when? how long? followed by imperfect Exodus 10:7 למוקשׁ לנו זה יהיה מתי עד, 1 Samuel 1:14; Jeremiah 4:14, 21; Psalm 74:10; 82:2; 94:3; Proverbs 1:22 +, followed by participle1 Sam 16:1; 1 Kings 18:21 הַסְּעִמִּים עַלשְֿׁתֵּי מֹּסְחִים אַתֶּם עַדמָֿתַי, followed by perfect Exodus 10:3; Psalm 80:5; לֹא מָתַי עַד 2 Samuel 2:26; Hosea 8:5; Zechariah 1:12; alone, Isaiah 6:11 אֲדֹנָי עַדמָֿתַי וָאֹמַר, Habakkuk 2:6 עַדמָֿתַי לֹאלֿוֺ הַמַּרְבֶּה הוֺי; with an aposiop., Psalm 6:4 י ׳וְאַתָּה עַדמָֿתָ֑י, 90:13.
d. עוֺד מָתַי אַחֲרֵי, after how long yet? Jeremiah 13:27.
מְתִים see מַת. מַתְכֹּ֫נֶת see תכן. above,
מַתְּלָאָה see תְּלָאָה. מְתַלְּעוֺת see תלע.
מְתֹם see תמם; Judges 20:48 see מַת.
מתן (√ of following; Arabic be stout, firm, enduring (Frey Wahrm), II. make stout, firm (Lane)).