The opposite of heavy is...
light
The opposite of safe is...
dangerous
The opposite of soft is...
hard
The opposite of right is...
wrong
The opposite of high is...
low
The opposite of hot is...
cold
The opposite of big is...
small
The opposite of easy is...
difficult
The opposite of cheap is...
expensive
The opposite of slow is...
fast
The opposite of narrow is...
wide
The opposite of interesting is...
boring
The opposite of long is...
short
The opposite of noisy is...
quiet
The opposite of relaxing is...
stressful
The opposite of early is...
late