transitive verb applied -·plied′, applying -·ply′·ing

1. to put on or spread on; place so as to be touching to apply a salve to the skin
2. to put to some practical or specific use to apply one's knowledge to a problem
3. to refer to a person or thing with (an epithet or suitable term)
4. to concentrate (one's faculties) on; employ (oneself) diligently to apply oneself to one's work

Etymology: ME applien < OFr aplier < L applicare, to attach to < ad-, to + plicare, to fold: see ply

intransitive verb

1. to make a formal request (to someone for something)
2. to be appropriate, suitable, or relevant this principle always applies