Something mailed by a seller to a collector to match their stated interests; the collector can approve of or return the item.
An expression granting permission; an indication of agreement with a proposal; an acknowledgement that a person, thing, or event meets requirements.
An expression of favorable acceptance and encouragement; a compliment that also condones.
Doubt; the condition of being uncertain or without conviction.
A parameter that measures the dispersion of a range of measured values.
Something uncertain or ambiguous.