• enPR: krĭsʹ-məs-trē, IPA: /ˈkɹɪsməs tɹiː/

Christmas tree (plural Christmas trees)

1. A conifer used during the Christmas holiday season, typically decorated with lights and ornaments and often a star or angel at its tip.
   • 1994, Stephen Fry, chapter 2, in The Hippopotamus:

     At the very moment he cried out, David realised that what he had run into was only the Christmas tree. Disgusted with himself at such cowardice, he spat a needle from his mouth, stepped back from the tree and listened. There were no sounds of any movement upstairs: no shouts, no sleepy grumbles, only a gentle tinkle from the decorations as the tree had recovered from the collision.

2. (informal, by extension) Anything elaborately ornamented or decorated.
   • 1985, Forbes, volume 135:

     The modern infantryman is a Christmas tree of weaponry, with grenades and extra ammunition hanging from all parts of his upper body.

3. (racing) A pole with lights, similar to a traffic signal, used for signalling the start of an automobile race.
4. (oil industry jargon) The collection of valves sometimes found at the top of a working oil well.
   • 2011, Robert Heidersbach, Metallurgy and Corrosion Control in Oil and Gas Production, →ISBN, page 232:

     Wellheads, which support downhole tubing, casing, and other components, are connected at the top of wells to Christmas trees, which control production rates and fluid flows out of the well and may also direct fluids and equipment into the well

5. (bodybuilding) A pattern of muscles visible in the lower back, resembling in outline the shape of a conifer.
   • 2013, Cory Gregory, “Get Jacked! The 1,000 Rep Workout”, in Fitness Rx, 11(4): 56:

     These are great for really developing that Christmas tree in your lower back and the proper arch at the top is key in that regard.

6. (aviation, historical) A type of alert area constructed by the Strategic Air Command of the United States Air Force during the Cold War.
7. (military, slang) A panel of indicator lights in an aircraft or a submarine.

• holiday tree

• French: arbre de Noël, sapin de Noël
• German: Weihnachtsbaum, Christbaum
• Italian: albero di Natale
• Portuguese: árvore de Natal, pinheiro de natal, pinheirinho
• Russian: ёлка
• Spanish: árbol de Navidad

• Russian: фонтанная арматура