Definition of "onset" in English

noun

1. (medicine) The initial phase of a disease or condition, in which symptoms first become apparent.

   • the onset of schizophrenia

2. (phonology) The initial portion of a syllable, preceding the syllable nucleus.

3. (acoustics) The beginning of a musical note or other sound, in which the amplitude rises from zero to an initial peak.

4. A setting about; a beginning.

   • the onset of puberty

5. (obsolete) Anything added, such as an ornament or as a useful appendage.

6. (archaic) An attack; an assault especially of an army.

verb

1. (obsolete) To assault; to set upon.

2. (obsolete) To set about; to begin.