Synonyms:
* Floatation: This refers to the ability to stay afloat on a liquid.
* Upthrust: This is the upward force exerted by a fluid on an object submerged in it.
* Levity: This refers to a lightheartedness or lack of seriousness, which can be a metaphorical synonym for buoyancy.
* Resilience: This refers to the ability to recover quickly from difficulties, which can be a metaphorical synonym for buoyancy.
Antonyms:
* Sinking: This refers to the opposite of floating, or the act of going down in water.
* Gravity: This is the force that pulls objects towards the center of the Earth, the opposite of buoyancy.
* Depression: This refers to a state of low spirits or sadness, which is the opposite of the metaphorical meaning of buoyancy.
* Despondency: This refers to a state of loss of hope or courage, which is the opposite of the metaphorical meaning of buoyancy.
Remember that the specific synonym or antonym you choose will depend on the context in which you are using the word "buoyancy."