IPA: /ˈslaɪtli/
KK: /ˈslaɪtli/
To a small degree or extent; not very much.
The temperature has slightly increased since yesterday.
Slightly → It is formed from "slight" (from Old English *slyht*, meaning small or insignificant) and the suffix "-ly" (meaning in a manner of). The word "slightly" means in a small or insignificant manner.
Think of something that is 'small' or 'insignificant' ('slight') and how it is done 'in a manner' ('-ly'). This helps you remember that 'slightly' means to do something in a small way.