ACCORDING TO THE INTERPRETATION PROVIDED BY Targum Onkeles, the term "Tzadik Tomim" identifies Noach as a completely righteous person.
אלין תולדת נח נח גבר זכאי שלים הוה בדרוהי בדחלתא דיי הליך נח:
These are the progeny of Noach. Noach was a complete righteous man in his generations; Noach walked with reverence of God.
However, it should be noted that the cantillation marks (trop) separate the words "tzadik" and "tomim," suggesting that Noach was both righteous and complete, and in truth, they are fundamentally different from one another. Therefore, insight can be drawn from another instance of the term "Tomim," that which is noted in Parashas Shoftim (Deuteronomy 18:13).
תמים תהיה עם יהוה אלהיך:
You must be wholehearted with Hashem your God.
Rashi offers an alternative interpretation of the term "Tomim" in the context of that verse. According to Rashi, "Tomim" is defined as walking with God and not investigating the future.
תמים תהיה עם ה' אלהיך. התהלך עמו בתמימות, ותצפה לו, ולא תחקר אחר העתידות, אלא כל מה שיבא עליך קבל בתמימות ואז תהיה עמו ולחלקו:
Walk before him whole-heartedly, put your hope in Him and do not attempt to investigate the future, but whatever it may be that comes upon you accept it whole-heartedly, and then you shall be with Him and become His portion (Sifrei Devarim 173:3).
Considering Rashi's exposition, one may understand "Tomim" as an attribute of contentment, living in the present moment. A state of contentment, indicative of happiness, directly results from a close relationship with God and trusting in His plan. Conversely, those who omit God from their lives tend to search and probe the future restlessly, attempting to control their destiny, when in reality, all is determined by God. In life, the person who is "Tomim," - complete in their relationship with God and has faith that He will provide for them - will experience contentment. This was the defining trait of Noach, who was "Tomim" with God and entrusted that He would safeguard and care for him.
Moreover, Noach is also referred to as righteous, a term that denotes an individual who lives with a constant awareness of God's presence. The excellence of Noach lies in his state of contentment, which found favor in God's eyes.
Content = Living With God