Nonassertive and Unambitious

Nonassertive adjective - Not aggressively self-assured, though not necessarily lacking in confidence.

Unambitious and nonassertive are semantically related. In some cases you can use "Unambitious" instead an adjective "Nonassertive".

Unambitious adjective - Having little desire for success or achievement.

Nonassertive and unambitious are semantically related. You can use "Nonassertive" instead an adjective "Unambitious".