John Lawler mentioned the term "unreleased" in a comment. John Wells has a blog post saying he prefers the term "[no audible release](http://phonetic-blog.blogspot.com/2012/03/no-audible-release.html
)". Both terms have been used in linguistics to refer to the phenomenon that you discussed. The "release" is the stage of pronouncing a plosive--a consonant like /p t k b d g/--where airflow stops being obstructed by the relevant parts of the vocal apparatus (the lips for the labial plosives /p b/, parts of the tongue and the teeth or roof of the mouth for other kinds of plosives). An audible release sounds like a puff of air after the plosive.

See also [Araucaria's answer on this site](https://english.stackexchange.com/a/268491/77227).