adj

• (chemistry) Of the state of an element at the time it is being generated from some compound or transitioning from one state to another; Newly released from a compound (especially hydrogen and oxygen) by a chemical reaction or electrolysis and possessing heightened reactivity; Newly synthesized (especially protein or RNA) by translation or transcription.
  "There are no reasons for supposing that any of the residual atmospheric oxygen is immediately combined with fixed or nascent hydrogen, or hydrocarbonate, in the venous blood at 98°, by slow combustion, and consequently none for supposing that water is immediately formed in respiration."
• (heraldry) Naissant.
  "[…] charges of blazonry, bends sinister and bends dexter, lions couchant, lions nascent, and[…]"
• (mathematics, obsolete) Describing a quantity of object that is starting to grow from zero or an infinitesimal beginning. Also the creation or identification of an infinitesimal delta.
  "Fluxions are very nearly as the Augments of the Fluents, generated in equal, but infinitely ſmall parts of Time ; and to ſpeak exactly, are in the Prime Ratio of the naſcent Augments : but they may be expounded by any Lines that are proportional to ’em."