Childishly irritable and sulky.
Childishly irritable and sulky; showing a peevish, ill-tempered impatience, typically at not getting one's way.
Petulant captures the snippy, snappish flare of someone annoyed that the world has not bent to their wishes — an often childish ill humor (Merriam-Webster). It is sharper and more outward than sullen: where sullen broods in heavy silence, petulant snaps, whines, and complains. It overlaps with annoyance and a touch of anger but is pettier in scale, tied to small frustrations rather than grave grievance, and it carries a strong note of immaturity that resentment and contempt lack. Against sulky, the two are close kin — both childish and pouty — but petulant tends toward active peevish outbursts and snippiness, while sulky leans toward withdrawn, silent pouting.
1590s, originally "immodest, wanton, saucy," from French petulant (mid-14c.), from Latin petulantem (nominative petulans) "wanton, forward, saucy, insolent," present participle of petere "to attack, assail; strive after; ask for, beg" (from PIE root *pet- "to rush, to fly"). The modern sense "irritable, manifesting peevish impatience" is attested by 1775, probably by influence of "pet" (a fit of peevishness).
Petulant underwent a notable shift: its earliest English sense was "immodest, saucy, insolent," echoing the Latin petulans, but over the 18th century — by 1775 — it migrated to "peevish, irritably impatient," likely pulled by association with "pet" (a fit of ill humor) and words like "pettish." The modern sense, evoking a childish short temper, has been stable since.