meaning - Magnificent / Splendid / fabulous / sumptuous / marvelous

Many time my mind stops working when it comes to the usage and comprehension of English synonyms. Indeed, the vastness in English language make me puzzled for the proper use of the word in sentence. The reason is that one word has lot of synonyms and used based on condition.

In this time I can't distinguish the usage of following words :

Magnificent, Splendid, fabulous, sumptuous, marvelous

I am able to grab the meaning of these words through dictionary. Almost all dictionaries define these words as extremely, impressive, excellent.
I'm really puzzled to what extent we can use these words.

For instance, I supposed that

magnificent is appropriate to scenarios, splendid (formal word of fabulous) is used in appearance, character

Am I right ? I found many times these words are used interchangeably.

For ex : which is correct in following sentence

magnificent/awesome/splendid/fabulous book, job, dinner, day ?

please help regarding exact usage of these words adding more examples

Answer

You get a feeling for these adjectives, all of the type first-class, only if you look at the etymology.

Magnificent contains Latin magnus big, and ficere to make.

splendid from Latin splendidus adj bright, shiny

fabulous Latin, as in fables

sumptuous from Latin sumere/sumptus, to take. Something made by taking a lot of expensive material.

Marvelous, French/Latin. French la merveille wonder, Latin mirabilis wonderful.

For details see Etymonline or a Latin dictionary.