Final answer:
The subject is English and the adjective in question describes someone who is careful with money, with synonyms 'thrifty', 'skimpy' and antonyms 'wasteful', 'indulgent', 'lavish'. It is important to use adjectives selectively, as per Mark Twain's advice, to make writing more effective.
Step-by-step explanation:
The finding synonyms and antonyms for an adjective that means being careful with money and resources. The synonyms provided in the question are 'thrifty' and 'skimpy,' whereas the antonyms are 'wasteful,' 'indulgent,' and 'lavish.'
The adjective in question describes someone who is economical and avoids unnecessary expenditure. An example of using this adjective in a sentence would be, 'Her thrifty habits allowed her to save enough money for a trip abroad.' Mark Twain's advice about adjectives stresses the importance of selecting adjectives carefully to enhance writing rather than cluttering it with unnecessary descriptive words.
Effective use of adjectives adds precision and clarity to writing, as in the revised sentence provided in the example, which substitutes a dense description with a single term 'mosaics.'