tense

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

• noun A property of verbs in which the time of the action or state, as well as its continuance or completion, is indicated or expressed.
• noun A category or set of verb forms that indicate or express the time, such as past, present, or future, of the action or state.

from The Century Dictionary.

• Being in a state of tension; stretched until tight; strained to stiffness; rigid; not lax: often used figuratively.
• To make tense or taut.
• noun Time. See temps.
• noun In grammar: Time.
• noun One of the forms, or sets of forms, which a verb takes in order to indicate the time of action or of that which is affirmed: extended also to forms indicating the nature of the action as continued, completed, and the like.

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

• adjective Stretched tightly; strained to stiffness; rigid; not lax.
• noun (Gram.) One of the forms which a verb takes by inflection or by adding auxiliary words, so as to indicate the time of the action or event signified; the modification which verbs undergo for the indication of time.

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

• noun grammar Any of the forms of a verb which distinguish when an action or state of being occurs or exists.
• adjective Showing signs of stress or strain; not relaxed.
• adjective Pulled taut, without any slack.
• verb To make or become tense.

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

• verb become tense, nervous, or uneasy
• noun a grammatical category of verbs used to express distinctions of time
• adjective in or of a state of physical or nervous tension
• adjective pronounced with relatively tense tongue muscles (e.g., the vowel sound in `beat')
• verb become stretched or tense or taut
• verb cause to be tense and uneasy or nervous or anxious
• verb increase the tension on
• adjective taut or rigid; stretched tight