This is the 10835th most frequent Russian word.
выдумывать
To invent, make up, or fabricate.
Here, 'выдумывать' means 'to make up' or 'invent', used to describe the act of creating fictional content.
Я часто выдумываю интересные истории.
I often make up interesting stories.
In this context, 'выдумывать' conveys the idea of fabricating or coming up with something to serve as an excuse.
Не нужно выдумывать оправдания, просто скажи правду.
You don't need to fabricate excuses, just tell the truth.
The word 'выдумывать' in this sentence signifies the process of thinking creatively to devise or craft a plan.