POSITIVE

One of two signs in this puzzle

• 100% sure

• Absolutely certain

• Certain

• Meaning of + on car-battery terminal

• One of your battery's terminals

• Optimistic

• Type of charge

• Upbeat

• Word (suggested by the black shape in this grid's center) that can precede the answers to starred clues

• A film showing a photographic image whose tones correspond to those of the original subject