1. a situation in which progress cannot be made
reach an impasse
An impasse can come about due to a disagreement, an insurmountable difficulty, or the refusal of the people involved in something to compromise. While sometimes it can lead to something failing to progress any further, often an impasse is a temporary stumbling block that requires cooperation and thinking outside the box to overcome. It can be used in either a social or professional context, but is more common in the latter. Two similar terms are 'stumbling block,' and 'sticking point.'