In phonetics, a plosive, also known as an occlusive or simply a stop, is a pulmonic consonant in which the vocal tract is blocked so that all airflow ceases.

The occlusion may be made with the tongue tip or blade ([t], [d]), tongue body ([k], [ɡ]), lips ([p], [b]), or glottis ([ʔ]). Plosives contrast with nasals, where the vocal tract is blocked but airflow continues through the nose, as in /m/ and /n/, and with fricatives, where partial occlusion impedes but does not block airflow in the vocal tract.

The terms stop, occlusive, and plosive are often used interchangeably. Linguists who distinguish them may not agree on the distinction being made. "Stop" refers to the stopping of the airflow, "occlusive" to the articulation which occludes (blocks) the vocal tract, and "plosive" to the plosion (release burst) of the consonant. Some object to the use of "plosive" for inaudibly released stops, which may then instead be called "applosives". The International Phonetic Association and the International Clinical Phonetics and Linguistics Association use the term "plosive".

Either "occlusive" or "stop" may be used as a general term covering the other together with nasals. That is, 'occlusive' may be defined as oral occlusive (plosives and affricates) plus nasal occlusives (nasals such as [m], [n]), or 'stop' may be defined as oral stops (plosives) plus nasal stops (nasals). Ladefoged and Maddieson (1996) prefer to restrict 'stop' to oral non-affricated occlusives. They say,

what we call simply nasals are called nasal stops by some linguists. We avoid this phrase, preferring to reserve the term 'stop' for sounds in which there is a complete interruption of airflow.

In addition, they restrict "plosive" for pulmonic consonants; "stops" in their usage include ejective and implosive consonants.

If a term such as "plosive" is used for oral non-affricated obstruents, and nasals are not called nasal stops, then a stop may mean the glottal stop; "plosive" may even mean non-glottal stop. In other cases, however, it may be the word "plosive" that is restricted to the glottal stop. Generally speaking, plosives do not have plosion (a release burst). In English, for example, there are plosives with no audible release, such as the /p/ in apt. However, English plosives do have plosion in other environments.

In Ancient Greek, the term for plosive was ἄφωνον (áphōnon), which means "unpronounceable", "voiceless", or "silent", because plosives could not be pronounced without a vowel. This term was calqued into Latin as mūta, and from there borrowed into English as mute. Mute was sometimes used instead for voiceless consonants, whether plosives or fricatives, a usage that was later replaced with surd, from Latin surdus "deaf" or "silent", a term still occasionally seen in the literature. For more information on the Ancient Greek terms, see Ancient Greek phonology § Terminology.