ectasis

from The Century Dictionary.

• noun In anc. orthoëpy and prosody: The pronunciation of a vowel as long.
• noun The lengthening or protraction of a vowel usually short. See diastole.
• noun In ancient rhetoric: The use of a long vowel or syllable in a part of a clause or sentence where it will produce a special rhythmical effect.
• noun The use of a form of a word longer than that commonly employed. This is generally called paragoge.

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

• noun (Pros.) The lengthening of a syllable from short to long.

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

• noun dilatation: for example, bronchiectasis, which refers to a pathologic dilatation of the bronchi of the lung.
• noun The lengthening of a syllable from short to long.

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

• noun dilatation or distension of a hollow organ