heighten

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

• intransitive verb To raise or increase the quantity or degree of; intensify.
• intransitive verb To make high or higher; raise.
• intransitive verb To rise or increase in quantity or degree; intensify.
• intransitive verb To become high or higher; rise.

from The Century Dictionary.

• To make higher; increase the vertical elevation of.
• To make higher in amount or degree; increase; augment; intensify: as, to heighten an effect.
• To make high or higher in feeling or condition; elevate or exalt, as the mind or a person.
• Synonyms Lift, Exalt, etc. See raise.
• To become higher; increase; augment.

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

• transitive verb To make high; to raise higher; to elevate.
• transitive verb To carry forward; to advance; to increase; to augment; to aggravate; to intensify; to render more conspicuous; -- used of things, good or bad

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

• verb To make high; to raise higher; to elevate.
• verb To carry forward; to advance; to increase; to augment; to aggravate; to intensify; to render more conspicuous; -- used of things, good or bad; as, to heighten beauty; to heighten a flavor or a tint.

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

• verb make (one's senses) more acute
• verb become more extreme
• verb increase the height of
• verb make more extreme; raise in quantity, degree, or intensity
• verb increase
• verb make more intense, stronger, or more marked