1. A competency or ability whose quality, reliability, or legitimacy is uncertain or doubtful
His questionable skill at negotiation has cost the company several important deals.
Sua habilidade questionável em negociação custou à empresa vários negócios importantes.
2. An ability that is subject to doubt or skepticism regarding its effectiveness
The magician's questionable skill at sleight of hand was exposed by the audience.
A habilidade questionável do mágico em prestidigitação foi exposta pelo público.