precursor

As nouns the difference between precursor and sigh

is that precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events while sigh is a deep and prolonged audible inspiration or respiration of air, as when fatigued, frustrated, grieved, or relieved; the act of sighing.

As a verb sigh is

to inhale a larger quantity of air than usual, and immediately expel it; to make a deep single audible respiration, especially as the result or involuntary expression of fatigue, exhaustion, grief, sorrow, frustration, or the like.

As an interjection sigh is

an expression of fatigue, exhaustion, grief, sorrow, frustration, or the like, often used in casual written contexts.

As a noun precursor

is that which precurses, a forerunner, a predecessor, an indicator of approaching events.

As a proper noun aura is

shortened from aurelia.

As nouns the difference between precursor and successor

is that precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events while successor is a person or thing that immediately follows another in holding an office or title.

As a noun precursor

is that which precurses, a forerunner, a predecessor, an indicator of approaching events.

As a verb foreshadow is

to presage, or suggest something in advance.

As nouns the difference between precursor and hazard

is that precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events while hazard is (historical) a type of game played with dice.

As a verb hazard is

to expose to chance; to take a risk.

As nouns the difference between introduction and precursor

is that introduction is the act or process of introducing while precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events.

As nouns the difference between precursor and predictor

is that precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events while predictor is something that anticipates, predicts or foretells.

Precursor is a related term of prognostic.

As nouns the difference between precursor and prognostic

is that precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events while prognostic is (rare|medicine) prognosis.

As an adjective prognostic is

of, pertaining to or characterized by prognosis or prediction.

Intelligencer is a related term of precursor.

As nouns the difference between intelligencer and precursor

is that intelligencer is (dated) a bringer of intelligence (news, information); a spy or informant while precursor is that which precurses, a forerunner, a predecessor, an indicator of approaching events.

In chemistry terms the difference between catalyst and precursor

is that catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process while precursor is one of the compounds that participates in the chemical reaction that produces another compound.