I need help finding a scientific term?

What is a scientific term that describes objects that exist only in our minds aka an abstract idea such as time? It a very specific word only used for

What is a scientific term that describes objects that exist only in our minds aka an abstract idea such as time? It a very specific word only used for this purpose especially when talking about the theory of time in quantum science. I have been looking for days to find the word that describes this category of intangible objects, but despite my efforts I have failed. This word is not very common and I believe only really used in the science world. Thank you!

or:What is a scientific term that describes objects that exist only in our minds aka an abstract idea such as time? It a very specific word only used for this purpose especially when talking about the theory of time in quantum science. I have been looking for days to find the word that describes this category of intangible objects, but despite my efforts I have failed. This word is not very common and I believe only really used in the science world. Thank you!

or:abstract - adj conceptual, theoreticalabstrusehypotheticalphilosophicalunrealcomplexdeepidealintellectualindefinitenonconcretereconditetranscendenttranscendentalMore: www.thesaurus.com/browse/abstract?s=t

Tags:mind,