certainly | The information is supported by primary sources. |
probably | The information is supported by secondary sources which is most likely based on primary sources. |
possibly | It is unclear if the secondary source cited is based on primary sources, or the information is an assumption well supported by other evidence. |
likely | The information is only found in secondary sources with questioned quality, or there is a reason to suspect the information is wrong. Or the information is a likely assumption based on other evidence. |
apparently | The information is doubtful and poorly documented, but still most likely correct. |
perhaps | The information might be correct or it might be wrong. It is not supported by any trustworthy sources. It might me an assumption. |
disproved | The information is proven to be wrong. |