The antonyms for the word "most confiding" would include words such as distrustful, guarded, suspicious, cautious, and reserved. When someone is described as being "most confiding," it suggests that the individual is open, sincere, and trusting. Conversely, if someone is seen as being distrustful or guarded, it implies that they are not willing to divulge personal information easily. A person who is described as suspicious is likely to be cautious and doubtful of others' motives, whereas someone who is cautious is careful when sharing information. Finally, a reserved individual may be quiet and shy, keeping their thoughts and feelings to themselves.