(see also Cul-de-sac)
(1) If in a dream you are - or feel - cornered, this w ill symbolize some frustration in yourself, the causes of which may be internal or external. In either case, you are being called on to make a decision. Ultimately the choice is between sliding into a neurosis and taking control of the situation (internal or external).
(2) Turning a comer, on the other hand, may signify taking a new direction in life; taking a turn for the better. See also Left, Right / Left.