Unreal means not real, or too strange to feel real. An unreal feeling, it was unreal, unreal expectations.
The plain sense is imaginary. The commoner spoken sense is that something actually happened but did not feel as though it did — the whole day felt unreal — which is a genuine psychological state called derealisation when it persists. In informal use, unreal is also a term of enthusiastic praise: the goal was unreal. Note surreal, which is close and means dreamlike.
1adjectiveunrealToo strange to feel real.
“Standing on the stage in front of thousands of people felt completely unreal.”
2adjectiveremarkableRemarkable, in informal praise.
“That goal was unreal! How did he score from so far out?”
unreal is a quality of unreality.
Middle English
real
English
real
English, today
unreal
From un- + real. real comes from Middle English real. From Middle English real, from Old French reel, from Latin reālis (“actual”), from Latin rēs (“matter, thing”), from Proto-Indo-European reh₁ís (“wealth, goods”). a doublet of realis.
Etymology from Wiktionary, CC BY-SA