1. n. the degree to which values predicted by a model correspond with empirically observed values. For example, in structural equation modeling, a researcher may want to see how well his or her hypothesized model of the relationships among a set of variables actually fits the variation and covariation in the data.

2. n. a lay term for an epileptic seizure.

3. n. a colloquial name for an emotional outburst.

4. adj. see fitness.