to know, recognize or understand something, especially something that is not obvious (Oxford)
2. to see, recognize, or understand something that is not clear (Cambridge)
He discerned a certain coldness in their welcome. (Oxford)
I quickly discerned that something was wrong. (Oxford)
discerned a certain coldness in their welcome
quickly discerned that something was wrong
Figure out
Detect
Confuse
Doubt
Discernible