opener

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

• noun One that opens, especially a device used to cut open cans or pry up bottle caps.
• noun The player who starts the betting in cards.
• noun Cards of sufficient value to enable the holder to open the betting.
• noun A remark that initiates a conversation.
• noun The first act in a theatrical variety show.
• noun Sports The first game in a series.
• idiom (for openers) To begin with.

from The Century Dictionary.

• noun plural In poker, the necessary qualification for opening a jack-pot, namely, jacks or better.
• noun One who opens: as, a pew-opener.
• noun A tool or machine used in opening.

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

• noun One who, or that which, opens.
• noun A bottle opener or a can opener.

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

• noun A device that opens something; specifically a tin-opener/can-opener, or a bottle opener.
• noun card games The player who starts the betting.
• noun card games (in plural openers) Cards of sufficient value to enable a player to open the betting.
• noun theater The first act in a variety show.
• noun cricket A batsman who normally plays in the first two positions of an innings.
• noun colloquial The first in a series of events, items etc.; the first remark or sentence of a conversation.
• noun sports The first game played in a competition
• noun sports The first goal or point scored.

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

• noun a hand tool used for opening sealed containers (bottles or cans)
• noun the first event in a series
• noun a person who unfastens or unwraps or opens