Effective, effectual, efficacious, productive, industrious.
Words that mean the same as the word 'beginning' are: start, origin, outset, onset, inception, source...
elevated.
The best word for "words that mean the same thing" is synonym. A synonym for big is large, for example.
The word for a word that is similar to another in meaning is synonym.
Absent
Synonyms are the different words that mean the same thing. Like for the word mean, a synonym would be unkind. Antonyms are words that mean the opposite of a word. For the word mean, an antonym might be nice.
Verbatim.
encluded
Split Shared by
both of the words are real and both mean the same thing, a fear of long words
I have seen the word "doublet" used to mean two words that come from the same root word.
Attempting, endeavoring.