Due to the general acceptance of 'manchild' as an unwanted negative stigma, let me offer an alternative take to the definition. A manchild is not necessarily bad, in fact it can be a good trait. A manchild could come to mean that the person retains childish aspects that are beneficial. For example, the childish aspect of being playful and finding playfulness in everyday sober life is beneficial to one's mental health. It could also imply the male individual retaining the "cute" and "bubbly" aspects from childhood that are often lost in adulthood (because of society's expectations for men to be rational and to hide their emotions). Furthermore, a manchild may still crush on a women and have infatuated feelings for them, and that's perfectly okay.

So in conclusion: manchild..... not a bad thing per se.

A male who is "of age" but still has the emotional/mental capacity of a child.

Completely incapable of making decisions regarding women, "manning up" when appropriate or discussing anything maturely, manchildren are becoming increasingly more frequent.

Manchildren will have notable traits such as thinking that they are somewhat different to other men because they have no emotional baggage, will find most immature humour widely entertaining and will have not been in a serious relationship, EVER. Longest relationship will be between 1-3 months.

When discussing important things, a man child will look at the floor and remain silent, pretend nothing is wrong at the time and then once out of sight drop into radio silence or will give you the "rabbit caught in the headlights" look.

However, man children are tempting challenge for women and more often than not an older women will take a man child under her wing as he will be impressed with her "at ease and coolness" and she will be taken back at his emotional naivety.

A man child is very easy to train in the ways of the bedroom.

A child who outwardly appears like an adult -- conventionally this means a full grown male that acts immaturely, or pursues childish interests. For example, it's acceptable to play games like World of Warcraft, but it's generally unacceptable to spend twelve hours a day doing so and/or attending conventions.

Manchildren, of course, are not limited to gamers. There are many types and variants of 'not-quite-men, but look-like-men.'

Donald J. Trump

Trump. Him and anything associated to his madness.

a teenager who is so large he could be a full grown man

Rush Limbaugh

a very large husky, hot, sexy, steamy man who can drink beer for breakfast and often grunts in the AM

An overweight, pill-popping, vain, whiney, paranoid, self-involved, clueless neo-con nimrod who loves the sound of his own voice who exploits the freedom to speak.