Accidental-happening or existing by chance
The problem is accidental, but the consequences can be fatal-Adjective
Assemble-to come together in a single place or bring parts together in a single group
verb-Assemble a team of legendary heroes in this Android game.
Calculate-to judge the number or amount of something by using the information that you already have, and adding, taking away, multiplying, or dividing numbers
Verb-Calculate the volume of a sphere with v = 4/3πr3.