This is the 48th most frequent Afrikaans word.
onder
"Onder" means "under" or "below" in English.
Here, 'onder' is a preposition indicating the position or location of an object relative to another.
Die boek is onder die tafel.
The book is under the table.
Here, 'onder' is used in an idiomatic phrase to describe a situational state, conveying the experience of pressure or stress.
Ek voel soms onder druk by die werk.
I sometimes feel under pressure at work.
In this instance, 'onder' describes the child being exposed to or within the rain, reflecting a metaphorical relation.