This is the 672nd most frequent Icelandic word.
fjölgað
"Increased" or "multiplied."
The word 'fjölgað' here is used to indicate an increase in quantity or number.
Þeim hefur fjölgað í hópnum.
They have increased in number in the group.
Here, 'fjölgað' refers to actively increasing the number of a certain entity, in this case, trees.
Við höfum fjölgað trjánum í garðinum.
We have multiplied the trees in the garden.
In this sentence, 'fjölgað' describes a natural or contextual increase in quantity.