DANGEROUS GOODS – Any article or substance which, when transported by air, may constitute a risk for health, security, property or environment and which is included in the list of the Technical Instructions of Dangerous Goods provided by the ICAO (document 9284) or that classified as such.
There are restrictions on the transport of dangerous goods not only regarding hold baggage but hand baggage as well, for which you may consult the list made available for you on the passenger link/portal.