```json
{
    "no": ["no"],
    "yes": ["yes"]
}
```

Based on the feature description and task, the possible values for the feature "default" are 'no' and 'yes'. Since the target is whether the client subscribes to a term deposit or not, the relationship between the feature and task can be analyzed as follows:

- Clients who have 'no' default (i.e., no credit in default) may be more likely to subscribe to a term deposit.
- Clients who have 'yes' default (i.e., have credit in default) may be less likely to subscribe to a term deposit.

The dictionary provided includes the possible values for the feature 'default' for each of the target classes 'no' and 'yes'.