A spore was a structure used by some fungi and plants in order to reproduce themselves asexually.
In April of 2151, Commander Tucker and Sub-Commander T'Pol were exposed to protocystian spores on the planet Rigel X.
(ENT: "Broken Bow")
The following year, Phlox examined Travis Mayweather to ensure that he was not carrying protocystian spores. (ENT: "Singularity")
Agmar claimed as a descendant of 21st century Phylosians, his and others' spores were rendered "sterile" from Staphylococcus infection of that time period. (TAS: "The Infinite Vulcan")
In 2264, members of the Omicron colony were infected by Omicron spores
on the Omicron Ceti III. Three years later, the USS Enterprise arrived at the planet, and the crew was infected by the spores, but the actions of Captain Kirk were able to save them. (TOS: "This Side of Paradise")
In 2376, The Doctor sent Tom Paris and Neelix to the Wyanti system to gather spores that could be used to grow antiviral proteins. (VOY: "Live Fast and Prosper")