Puzzles/Word-In-Word

Word-in-word puzzles are word puzzles where the premise of the puzzles is to find words that all contain a certain other word hiding inside.

For example, all of the following words should contain the word tri:
 * "Tri" - comes from the Greek word treîs or tría meaning "three / 3"

TRI
Below are the samples of word-in-word puzzles starting with word tri

{ A shape with three straight sides and three angles { triangle | Triangle }
 * type="{}"}

{ A sporting event which there are 3 sporting categories: E.G: Running, swimming and cycling { triathlon | Triathlon }
 * type="{}"}

{ A vehicle which have one wheel at front and two at back { tricycle | Tricycle | trike | Trike }
 * type="{}"}

{ Happening every 3 years { triennial | Triennial }
 * type="{}"}

{ A long fork which has 3 sharp points { trident | Trident }
 * type="{}"}

{ A group of three related novels, movies { triology | Triology | trilogy | Trilogy }
 * type="{}"}

{ A metal stand with three feets to hold up cooking pots to be placed over fire { trivet | Trivet }
 * type="{}"}

{ A million million million { trillion | Trillion }
 * type="{}"}

{ A set of three children/animals born to same mother at the same time { triplet | Triplet }
 * type="{}"}