Lacuna

"Our young friend makes up for many obvious mental lacunæ by some measure of primitive common sense," remarked Challenger.

Long lacunae in this inscription make interpretation difficult.

For Beatrice Nutter, there will always be conspicuous lacunae in our mutual understanding, but after almost 30 years here, the anomalies now delight rather than confound her.

If the researcher cannot adequately hear a specific conversation due to its low volume or other acoustic interference, then this data point can be passed over with the understanding that such lacunae will be randomly distributed over the data collecting period.