Meaning trap
make up
invent (a story, excuse, etc.)
To create something that is not true, such as a story or an excuse.

Don't mix these meanings
Same phrase, different job.
To create something that is not true, such as a story or an excuse.
Another meaning of 'make up' is 'become friends again after an argument'; compare the examples to keep the meanings separate.
Hear it in context
Notice where the phrase sounds natural.
He made up an excuse for being late.
In some situations, people might make up stories to avoid getting into trouble.
Fix the pattern
One small grammar move makes it sound right.
Not: He made up it.
Say: He made it up.
Separable: 'make up a story' or 'make a story up'; with a pronoun, 'make it up'.
Which sounds natural?
Tap the one a native speaker would say.
'Make up' is the everyday verb for inventing a story/excuse; 'fabricated a justification' is formal/legalistic.
Build natural chunks
Words that usually travel with it.
make up + fiction
- an excuse
- a story
- a name
- the whole thing
Don't confuse it
Related
Other meanings and phrases to compare.
- make up (become friends again) — Another meaning of 'make up' is 'become friends again after an argument'; compare the examples to keep the meanings separate.