Which term would best describe an action done with a sense of friendliness?

The term that best describes an action done with a sense of friendliness is "cordial." This word conveys warmth and a welcoming attitude, reflecting positive feelings towards others. When actions are characterized as cordial, it implies that they are undertaken with kindness and good intent, fostering a friendly atmosphere.

The other options do not carry the same connotations. For example, "counterfeit" refers to something that is made to imitate something else, often with harmful intent, rather than conveying friendliness. "Curtail" means to reduce or limit something, which does not align with the idea of friendliness. Similarly, "cumbersome" describes something that is awkward or difficult to manage, which also lacks the warm and inviting essence associated with friendly actions. Thus, "cordial" is the most appropriate choice for actions imbued with friendliness.