IPA: /ˌʌn.kənˈtɛn.ʃəs/
KK: /ʌnˈkɒn.tɛn.ʃəs/
Not causing or likely to cause disagreement or controversy.
The meeting was uncontentious, with everyone agreeing on the proposed changes.
Uncontentious → It is formed from "un-" (meaning not) and "contentious" (from Latin "contentiosus", meaning quarrelsome or argumentative). The word "uncontentious" means not quarrelsome or not likely to cause disagreement.
Think of 'not' ('un-') being added to 'quarrelsome' ('contentious') — that's why uncontentious means not likely to cause arguments.