Antonyms

Noble is the correct antonym of Base. In moral context, base means lacking moral dignity or being of inferior character (like immoral or vile). Noble means having high moral qualities or being dignified. Immoral, wicked, and vile are synonyms of base, not antonyms.

Important is the correct antonym of Un-essential. Essential means absolutely necessary or extremely important. Un-essential means not necessary or not crucial. Important is the best antonym available, though 'essential' would be more precise. Supplementary, inferior, and secondary are not opposites.

Precious is the correct antonym of Worthless. Worthless means having no value, use, or importance. Precious means of great value, highly valued, or cherished. Poor, futile, and miserable are not true antonyms - they can describe negative states but don't directly oppose 'worthless'.

Dullness means lacking interest, excitement, brightness, or animation. Liveliness directly opposes this by meaning full of energy, vitality, and spirited activity.

Invariable means unchanging, constant, or not subject to variation. Flexible means capable of change or adaptation - the direct opposite of something fixed or rigid.

Sameness means being identical, uniform, or exactly like something else. Difference means being distinct, dissimilar, or not the same - directly opposing uniformity.

Inexperienced means lacking practice or skill, while practised means having gained skill through repeated application. Practised directly opposes the state of being inexperienced.

Persistent means continuing without interruption, while irregular describes something happening at inconsistent intervals. This captures the contrast between steady continuity and sporadic occurrence.

Untouched means something remains in its original state without being influenced, while affected describes something that has been changed or impacted by external forces.

Factitious describes something artificial or contrived, while natural refers to something occurring in nature without human intervention. These represent opposing origins - artificial versus genuine.

Grim means serious, stern, gloomy, or forbidding in appearance or manner. This directly contrasts with cheerful, which means happy, joyful, or displaying good humor. Happy, jocund, and jolly are all synonyms or near-synonyms of cheerful.

Irresponsible means not reliable or trustworthy, lacking a sense of responsibility. This is the opposite of reliable, which means consistently good in quality or performance and able to be trusted. Honest and trustworthy are actually similar in meaning to reliable, while wisdom is unrelated.

Singular means unique, exceptional, remarkable, or unusual. Common means ordinary, widespread, or frequently occurring - the opposite of being unique or exceptional. Remarkable, peculiar, and unique are all synonyms or near-synonyms of singular.

Ugly means unpleasant or unattractive in appearance, which is the direct opposite of good-looking (attractive). Smart refers to intelligence, timid refers to shyness, and elegant is actually similar in positive connotation to good-looking. The contrast is purely about physical appearance.

Steady is the correct antonym of changeable because it means stable, constant, and not varying. The other options (uncertain, erratic, volatile) are actually synonyms or related concepts to changeable, not antonyms.