1. （药物等的）过量；致死（或中毒）剂量
If someone takes an overdose of a drug, they take more of it than is safe.

2. 过量服用（药物）；过量吸食（毒品）
If someone overdoses on a drug, they take more of it than is safe.

3. （尤指有害物的）过量，过多
You can refer to too much of something, especially something harmful, as an overdose.

4. 过多拥有；沉溺
You can say that someone overdoses on something if they have or do too much of it.

1. dose too heavily

e.g. The rock star overdosed and was found dead in his hotel room

Synonym: o.d.