架空【かくう】
fictitious, imaginary, fanciful, fabricated, aerial, overhead
十字架【じゅうじか】
cross (for crucifixion), the Cross (of Christ)
担架【たんか】
stretcher, litter (medical), gurney
架設【かせつ】
construction, building
架橋【かきょう】
bridge-building, bridge construction, bridge, bridging (e.g. the gap between theory and practice), cross-linking
書架【しょか】
bookshelf, bookcase