The act of sustaining or support
Sustenance
Writing written on a tombstone
Epitaph
A mark on the surface of something
Imprint
Unimportant/irrelevant or spiritual
Immaterial
Not feeling ashamed for doing something
Impenitent
Calm or in control
Imperturbable
Unable to be perceived
Imperceptible
To treat everyone equally
Impartial
Not allowing liquids to pass through or not affected by
Impervious
Not reasonable or realistic
Implausible
An enclosed garden or religious place
Cloister
An open-air place with land dug up or a prey
Quarry
A place that is sealed from visitors
Enclosure
To become narrower
Constricting
Extremely serious or urgent
Dire
A restriction
Stricture
Prevented something from happening
Preclude