adjective

1. not quick or clever in understanding; dull; obtuse
2. 1. taking a longer time than is expected or usual to act, move, go, happen, etc.
   2. not hasty, quick, ready, or prompt a slow retort, slow to anger
3. making relatively little progress for the time spent; marked by low speed, rate of rhythm, etc.; not fast or rapid
4. holding back fast progress, development, etc.; making speed or progress difficult a slow growing season, a slow track
5. showing a time that is behind the correct time: said of a timepiece
6. 1. passing slowly or tediously a slow afternoon
   2. not lively or interesting; dull or boring a slow town
7. characterized by little activity; slack slow trading
8. lacking in energy; sluggish
9. behind the times; out of fashion
10. burning so as to give off a low or moderate heat a slow fire
11. gradual, as growth
12. Photog.
    1. having less sensitivity to light than other film, etc.: such film may require a longer exposure period
    2. allowing less light to enter than other lenses

Etymology: ME slowe < OE slaw, akin to Du sleeuw, ON slær, dull < ?

transitive verb

1. to make slow or slower
2. to retard; delay

intransitive verb

adverb