sensitize

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To make sensitive.
• intransitive verb To make (a film or plate) sensitive to light, especially to light of a specific wavelength.
• intransitive verb To make hypersensitive or reactive to an antigen, such as pollen, especially by a second or repeated exposure.
• intransitive verb To become sensitive or hypersensitive.

from The Century Dictionary.

• To render sensitive; specifically, in photography, to render capable of being acted on by actinic rays of light: as, sensitized paper, or a sensitized plate. See sensitized paper, under paper.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb (Photog.) To render sensitive, or susceptible of being easily acted on by the actinic rays of the sun.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To become increasingly aware of, in a concerned or sensitive way.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb make sensitive to a drug or allergen
• verb cause to sense; make sensitive
• verb make (a material) sensitive to light, often of a particular colour, by coating it with a photographic emulsion
• verb make sensitive or aware