The dictionary is only a start, and not always a good one, for concepts like “voice.” Dictionary definitions are often inadequate enough for words like “love” and “art” and when it comes to metaphors like “voice” a dictionary is often helpful only as a very basic start of a wider discussion. Leibovitz and Karsh were both more style than voice and that’s the part that can be imitated. If one has his or her own voice as a portrait photographer and chooses to imitate Leibovitz or Karsh on occasion, it will make sense relative to their own body of work and the meaning and feeling of the adopted style will likely be somewhat transformed, even while still being a reference, by the new voice taking it up. “Good artists copy, great artists steal” because great artists, when they lift styles or elements of others’ work, make it their own. Two portrait photographers who strike me as having important and unique voices are Arbus and Stieglitz. Their voices were much more important and impactful than their styles.