There is no such thing. It makes sense to talk about opposites of simple properties (adjectives), such as "fast", "clever", etc.; in general, it doesn't make so much sense to talk about the opposites of objects (nouns).
what word is opposite of prudent
The opposite of anything is it's absence. Silence would be the opposite of a word spoken.
There is no opposite to cobble.
The word 'surf' does not have a opposite word.
injustice.The opposite word for justice is the word injustice.
Not sure what you mean by the opposite of nectar. Bees collect nectar and pollen from flowers.
nectar is what the bees drink
Beer is like the nectar of the gods
The flower's sweet nectar attracts bees to pollinate it. Bees gather nectar and make it into honey.
Royal Nectar
Pool of Nectar
No, nectar is a concrete noun; it is a substance produced by flowers. It is sometimes used in an abstract context, such as 'music is nectar for the soul', but the word itself is a concrete noun.
what word is opposite of prudent
The opposite of anything is it's absence. Silence would be the opposite of a word spoken.
Nectar is another name for ambrosia, the food of the gods (in Greek mythology) which when eaten grants immortality.
Opposite word of light
which is the opposite to the word satisfaccion