Unexpected is defined in dictionaries as meaning an event ‘not regarded as about to happen’. That is a clear definition. In practice the word has a range of meanings. For instance, unexpected can mean that an event was never thought of previously. Or it can mean that the event was thought of but the possibility of it happening was not allowed for. So knowing what was really meant when it is stated that a project was unexpected may be needed to help understand how that project was planned and managed.