Food Security is defined by the USDA as "access by all people at all times to enough food for an active, healthy life"
Food Sovereignty defined in the Declaration of Nyeleni as: Food sovereignty is the right of peoples to healthy and culturally appropriate food produced through ecologically sound and sustainable methods, and their right to define their own food and agriculture systems.
A useful site with a glossary of gardening terms can be found on Gardenary's blog.
The USDA has a Glossary of Terms as well.
Here are some useful terms to get you started:
Annual
Biannual
Bolting
Cold stratification
Dead heading
Direct sow
Frost hardy
GMO
Heirloom
Hybrid
Organic
Perennial
Plant Hardiness Zone