Verb

(obsolete) To go or move under or beneath.

To experience; to pass through a phase.

* {{quote-magazine, date=2013-01-01

, author=Paul Bartel, Ashli Moore , title=Avian Migration: The Ultimate Red-Eye Flight , volume=101, issue=1, page=47–48 , magazine= citation , passage=Many of these classic methods are still used, with some modern improvements. For example, with the aid of special microphones and automated sound detection software, ornithologists recently reported […] that pine siskins (Spinus pinus ) undergo an irregular, nomadic type of nocturnal migration.}}

The project is undergoing great changes.

To suffer or endure; bear with.

The victim underwent great trauma.

She had to undergo surgery because of her broken leg.

Verb

(head)

(undergo)

*

The repeated exposure, over decades, to most taxa here treated has resulted in repeated modifications of both diagnoses and discussions, as initial ideas of the various taxa underwent —often repeated—conceptual modification.