[schacon]

I understand, I meant I tried to say the word “decisecond” out loud and we debated if that was a real word or if I was attempting to say “deca” which was understandable.

[zxvkhkxvdvbdxz]

It's very standardized (SI), meaning 1/10:th. Althought not so commonly used with seconds.

You might be more familiar with decimeters, deciliters, decibels or the base-10 (decimal) numbering system.

[quesera]

Also "decimate" which used to mean "kill 1/10th of the soldiers", but now apparently means "destroy (almost) entirely". :)

[CRConrad]

Sure, deca- as in "decade" is understandable. But why would deci- as in "decimal" be any less understandable?