The word trajectory is a noun. The plural form is trajectories.
noun
Circumference is a noun.
"Ellipse" is a noun.
Quadrilateral can be used as a noun and an adjective.
A simile is not a part of speech; it is a figure of speech used in writing and speech to make comparisons between two different things using the words "like" or "as." For example, saying "as brave as a lion" is a simile that compares bravery to a lion. It enhances imagery and helps convey meaning more vividly.
A projectile has minimum speed at the top of the trajectory.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "twirl" is a verb.
The part of speech for "explicit" is an adjective.
The part of speech for "indefinite" is an adjective.
The part of speech for "lecturer" is a noun.