xenobiotic
Plastics or any synthetic substance as found in the atmosphere.

xerophlic fungi
Fungi that can grow in dry conditions.

xylene
C6H4(CH3), a toxic isomeric liquid.

xylophagous
The destroying of wood due to fungi.

yard lumber
General building lumber as graded by its size and length.

yellowing
A yellow cast on any clear, white or light colored material due to aging, heat, cleaning etc.

yeild strenght
Less than the allowable stress to strain, the ratio of stress to strain where the value has dropped below maximum attainable stress.

zinc
Zn, a metallic element as used in the galvanizing of steel, cathodic protection.

zinc chromate
A pigment used in paints as a rust-inhibiting agent.

zinc oxide
ZnO, a pigment used in primers and paints as a rust inhibitor.