Feeling worried about something you are going to do or that is going to happen. (Cambridge Dictionary)
Feeling anxiety about the future; featuring that something unpleasant will happen. (Cambridge Dictionary)
Viewing the future with anxiety or alarm : feeling or showing fear or apprehension about the future. (Merriam – Webster)
Capable of understanding or quick to do so: Discerning. (Merriam – Webster)
Having awareness or knowledge of something : Cognizant. (Merriam – Webster)
Anxious or fearful that something bad or unpleasant will happen. (Oxford Dictionaries)
Someone who is apprehensive is afraid that something bad may happen.
The Ambiguity of ‘Apprehension’
Apprehensive. Your Dictionary.