acceptable — Acceptable activities and situations are those that most people approve of or consider to be normal.
respectable — worthy of respect or esteem; estimable; worthy: a respectable citizen.
adequate — If something is adequate, there is enough of it or it is good enough to be used or accepted.
mediocre — of only ordinary or moderate quality; neither good nor bad; barely adequate: The car gets only mediocre mileage, but it's fun to drive. Synonyms: undistinguished, commonplace, pedestrian, everyday; run-of-the-mill. Antonyms: extraordinary, superior, uncommon, incomparable.
tolerable — capable of being tolerated; endurable: His arrogance is no longer tolerable.
so-so — Also, soso. indifferent; neither very good nor very bad.
allowable — If people decide that something is allowable, they let it happen without trying to stop it.
average — An average is the result that you get when you add two or more numbers together and divide the total by the number of numbers you added together.
common — If something is common, it is found in large numbers or it happens often.
fair — free from bias, dishonesty, or injustice: a fair decision; a fair judge.
middling — equally distant from the extremes or outer limits; central: the middle point of a line; the middle singer in a trio.
moderate — kept or keeping within reasonable or proper limits; not extreme, excessive, or intense: a moderate price.
ordinary — of no special quality or interest; commonplace; unexceptional: One novel is brilliant, the other is decidedly ordinary; an ordinary person.
unexceptional — not exceptional; not unusual or extraordinary.