noun
wooden block; wooden brick
A block of wood, often used as a toy building block or in construction. The reading きれんが is less common.
子供が木煉瓦で遊んでいる。
The child is playing with wooden blocks.
この木煉瓦は積み木として使えます。
These wooden blocks can be used as building blocks.
積み木 specifically refers to toy building blocks, while 木煉瓦 is a more general term for a wooden block or brick.
Compound of 木 (wood) and 煉瓦 (brick). The reading もくれんが is the standard on'yomi combination; きれんが is a mixed reading.