"Nailed one's colors to the mast" is an idiomatic expression that means to publicly declare one's beliefs, opinions, or intentions and be ready to defend them. There are a few synonyms that can be used in place of this expression, such as "taken a stand," "committed oneself," "declared one's position," or "set one's position in stone." All of these phrases have a similar meaning to "nailed one's colors to the mast" and emphasize the importance of standing firm in one's convictions. By declaring one's beliefs and remaining steadfast in them, individuals show their strength of character, determination, and willingness to fight for what they believe in.