anaplasia

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Reversion of cells to an immature or a less differentiated form, as occurs in most malignant tumors.

Century Dictionary and Cyclopedia

1. n. In pathology, the sum of the morphological, structural, chemical, and other alterations which cells undergo when assuming the characteristics of malignancy.
2. n. Same as anaplasis.

Wiktionary

1. n. biology A reversion of differentiation in cells that is characteristic of malignancy in tumours

GNU Webster's 1913

1. n. loss of structural differentiation within a cell or group of cells often with increased capacity for multiplication, as in a malignant tumor.

WordNet 3.0

1. n. loss of structural differentiation within a cell or group of cells often with increased capacity for multiplication, as in a malignant tumor