More formal:
* Bickering: This is a common synonym for squabbling, often used to describe petty arguments.
* Disputing: This suggests a more serious disagreement, but can still be used for smaller arguments.
* Contending: This implies a stronger disagreement and a desire to win.
* Feuding: This is used for a long-lasting, bitter dispute.
* Quarreling: This is another common synonym for squabbling, often used for more serious arguments.
* Wrangling: This suggests a more forceful, contentious argument.
More informal:
* Argue: This is a general term for any disagreement, but can be used for squabbling.
* Fighting: This is a more intense word than squabbling, but can be used for a more physical or emotional dispute.
* Grumbling: This suggests a more passive-aggressive form of squabbling.
* Nitpicking: This refers to finding fault with small details.
* Sparring: This suggests a more playful or lighthearted form of squabbling.
The best synonym to use will depend on the specific situation.