1. The abrupt and involuntary flow of speech or thought where a person is suddenly aware thatthey are not performing a certain mental act. Also called mental block. See retrieval block. 2. A percieved barrier that can't be crossed. 3. A physical, biological aor psychological barrier that obstructs or impedes a function or action. 4. In experimental block design, it is the levels or subsets where samples are divided. 5. The subdivide participants into groups. 6. To impede or obstruct.
BLOCK: "The mental block meant that Joe couldn't think of the word he wanted to use."