This came up recently in a session: Our cleric thought it would be a great idea if he made our airship hallowed.
The description of the hallow spell says:
You touch a point and infuse an area around it with holy (or unholy) power. The area can have a radius up to 60 feet, and the spell fails if the radius includes an area already under the effect of the hallow spell.
The DM disallowed it; he said it was meant to create hallowed ground, and by our interpretation, we'd be able to cast the spell on a rock and then just carry that rock around.
We countered with "Isn't our ship a place/area?" but he said "No," so we left the argument at that.
In the case of the silence spell vs the light spell, it's pretty clear one is attached to an object and the other is not.
The description of light says:
You touch one object [...] the object sheds bright light
On the other hand, silence says:
no sound can be created within or pass through a 20-foot-radius sphere centered on a point you choose within range.
But in the case of hallow, there's an ambiguous "touch" and "area" mentioned.
What constitutes a "point" and "area" for the hallow spell - especially when the spell description mentions touching it?