a a /eɪ/

article

1. () "A" is an indefinite article in English, used before singular nouns that are unspecified or not yet known to the listener. "An" is used before a vowel sound, "a" otherwise  ( a , an )
   "A" is an indefinite article in English, used before singular nouns that are unspecified or not yet known to the listener. "An" is used before a vowel sound, "a" otherwise
   

 A

noun

1. () A metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation  ( angstrom , angstrom unit , A )
   a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
    Light has a wavelength in the range of 400–700 nm.
   Light has a wavelength in the range of 400–700 nm.
   
   
2. The blood group whose red cells carry the A antigen  ( A , group A , type A )
   the blood group whose red cells carry the A antigen
   
3. The 1st letter of the Roman alphabet  ( A )
   the 1st letter of the Roman alphabet
   
4. The basic unit of electric current adopted under the Système International d'Unités  ( A , ampere , amp )
   the basic unit of electric current adopted under the Système International d'Unités
    A typical household circuit carries 15 to 50 amps
   a typical household circuit carries 15 to 50 amps
   
   
5. (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA  ( A , adenine )
   (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
   
6. One of the four nucleotides used in building DNA, also known as deoxyadenylate, or dAMP; all four nucleotides have a common phosphate group and a sugar (ribose)  ( A , deoxyadenosine monophosphate )
   one of the four nucleotides used in building DNA, also known as deoxyadenylate, or dAMP; all four nucleotides have a common phosphate group and a sugar (ribose)
   
7. Any of several fat-soluble vitamins essential for normal vision; prevents night blindness, inflammation or dryness of the eyes  ( A , antiophthalmic factor , axerophthol , vitamin A )
   any of several fat-soluble vitamins essential for normal vision; prevents night blindness, inflammation or dryness of the eyes
   

 Ouija board Ouija board /ˈwiːdʒə bɔːrd/

noun

1. A board with the alphabet on it; used with a planchette to spell out supernatural messages  ( Ouija , Ouija board )
   a board with the alphabet on it; used with a planchette to spell out supernatural messages
   
   

 Emerson Emerson /ˈɛmɝsən/

noun

1. United States writer and leading exponent of transcendentalism (1803-1882)  ( Emerson , Ralph Waldo Emerson )
   United States writer and leading exponent of transcendentalism (1803-1882)
   
   

 hunter hunter /ˈhʌntɝ/

noun

1. () Someone who hunts game  ( huntsman , hunter )
   someone who hunts game
     The skilled hunter tracked the elusive prey through the dense forest.
   The skilled hunter tracked the elusive prey through the dense forest.
   
2. A watch with a hinged metal lid to protect the crystal  ( hunter , hunting watch )
   a watch with a hinged metal lid to protect the crystal
   
   
3. A person who searches for something  ( hunter )
   a person who searches for something
    A treasure hunter
   a treasure hunter
   
   

 Hunter

1. A constellation on the equator to the east of Taurus; contains Betelgeuse and Rigel  ( Hunter , Orion )
   a constellation on the equator to the east of Taurus; contains Betelgeuse and Rigel