a (context|New Age jargon) (pejorative) bad, unwanted, disagreeable, potentially damaging, to be avoided, unpleasant, difficult, painful; (often precedes 'energy', 'feeling', 'emotion' or 'thought').
n (photography) an image in which dark areas represent light ones, and the converse (defdate|from the 19th c.)
n (weightlifting): A rep performed with weight in which the muscle begins at maximum contraction and is slowly extended; a movement performed using only the eccentric phase of muscle movement.