Here are some regularly used gardening terms and definitions, courtesy of the experts at the RHS...
Annual - a plant that completes its life cycle (germination, flowering, seeding, dying) in one growing season
Breaking bud - the stage of growth when a bud bursts through the protective bud scales
Broadcast sowing - scattering seeds evenly over the ground rather than in furrows or drills
Contact weedkiller - a weedkiller that kills by direct contact
Deciduous - describes plants that shed leaves at the end of the growing season and renew them at the beginning of the next
Drill - a narrow, straight furrow in the soil in which seeds are sown or seedlings planted
Evergreen - describes plants that retain most of their leaves throughout the year
Foliage - leaves
Germination - the physical and chemical changes that take place as a seed starts to grow and develop into a plant
Hardy - able to withstand year-round climatic conditions including frost, without protection
Medium - a growing mixture or other material in which plants may be grown
Organic matter - composts or similar materials derived from plant material
Perennial - any plant living for at least three years (annual = 1 year, biennial = 2 years)
Rootball - the roots and accompanying soil when a plant is removed from a container or lifted from the ground
Rosette - a cluster of leaves radiating from approximately the same point, often at ground level
Seedling - a young plant that has developed from a seed
Systemic / translocated weedkiller - a weedkiller that is absorbed and distributed through a plant when applied to leaves
Tilth - a fine crumbly surface layer of soil produced by cultivation