Actually, the question supposes that אָדוֹן (English transliteration: adon) and its 1st person pronominal inflection אֲדֹנֵנוּ (English transliteration: adonenu) are actual Aramaic words, but they are not (unless I am mistaken).
An an example, if I asked someone how to conjugate the Spanish verb llover (what we understand as the infinitive "to rain" in English) into German, you would get a puzzled look, because llover is simply not a German verb.
The Aramaic equivalent of the Hebrew word אָדוֹן is generally רַב. The inflection of the form indicating 1st person plural ("our") and a singular "lord" (opposed to "lords") would be רִבוֹנַנָא (English transliteration: rivonana).
As an example, see the Targum Yonatan of 1 Samuel 16:16:
Masoretic:
יֹאמַר-נָא אֲדֹנֵנוּ, עֲבָדֶיךָ לְפָנֶיךָ--יְבַקְשׁוּ, אִישׁ יֹדֵעַ מְנַגֵּן בַּכִּנּוֹר; וְהָיָה, בִּהְיוֹת עָלֶיךָ רוּחַ-אֱלֹהִים רָעָה--וְנִגֵּן בְּיָדוֹ, וְטוֹב לָךְ.
Targum Yonatan:
יֵימַר כְעַן רִבוֹנַנָא עַבדָך קֳדָמָך יִבעוֹן גֻברָא דְיָדַע לְנַגָנָא בְכִנָרָא וִיהֵי״והוה#3#״ כַד תִשרֵי עְלָך רֻוחַ בִישָא מִן קֳדָם יְיָ וִינַגֵין בִידֵיה וְיִיטַב לָך