(be in) build(-er, -ing, up), edify, embolden

Concise Bible Dictionary:

As early as Genesis 4:17 we read of Cain building a city and calling it after his son’s name; since which time building houses has become common; whereas Abraham looked for a city whose Builder is God. It is used as symbolical of raising up a spiritual edifice to God, of which Christ is the Builder (Matt. 16:18; 1 Cor. 3:9; Eph. 2:21; 1 Pet. 2:5). As instruments, others also are builders—Paul calls himself “a wise master builder,” or rather “architect” as having well laid the foundation of the assembly, which is Christ (1 Cor. 3:10). The laborers are cautioned as to the material they use in building up a house for God: improper materials will not stand the test of the fire, and the builders will suffer loss by seeing their work burned up and by losing their reward (1 Cor. 3:10-14). Whereas all that Christ builds, though by the instrumentality of His servants, will surely stand forever. Under another similitude Christ is the chief corner stone, or head of the corner, which “the builders,” the heads of the Jewish nation, refused, but which God exalted (Psa. 118:22; Matt. 21:42; Acts 4:11; Eph. 2:20; 1 Pet. 2:7).

Strong’s Dictionary of Greek Words:

Greek:
οἰκοδομέω
Transliteration:
oikodomeo
Phonic:
oy-kod-om-eh’-o
Meaning:
from the same as 3619; to be a house-builder, i.e. construct or (figuratively) confirm
KJV Usage:
(be in) build(-er, -ing, up), edify, embolden