Meaning : Something that always happens or something that is constant. In short, you use the word invariably, when discussing things that happen all the time or just don't change.
Mary invariably visits her grandmother every Saturday. This means, she regularly visits her grandmother every Saturday.
So basically, when an action is repeated regularly, you use the word invariably.
As the word invariably indicates that an action happening constantly, it is an Adverb.
Example 1 : Many people invariably start each morning with a hot cup of tea.
Ex 2 : Even though Sarah is on a diet, she invariably lands up eating something sweet at night.
Ex 3: The price of gold is invariably on a rise.
Ex 4 : In spite of repeated warnings, John is invariably late for the meetings.
Ex 5 : Peter invariably gets drunk in every party.
Ex 6 : Due to Rosie's efficiency, she invariably receives compliments from her boss for all her projects.
Ex 7 : The experienced boxer invariably wins every boxing match.
Ex 8 : Whenever Rams wears a white shirt, he invariably lands up spilling something over eat.
Ex 9 : Sam invariably forgets to charge his mobile phone, getting in touch with him is really difficult.
Ex 10 : Due to Kelly's positive approach towards life, she is invariably happy over years.