Eidolon

Eidolon (ahy-DOH-luhn) is a phantom; apparition; an ideal.

The word comes from the more common word, idol, which originally referred to pagan religious idols.

"It was the ghoulish shade of decay, antiquity, and desolation; the putrid, dripping eidolon of unwholesome revelation, the awful baring of that which the merciful earth should always hide." (H.P. Lovecraft, The Outsider)

Ectasis

Ectasis is an expansion or the lengthening of syllable from short to long.

As I understood its meaning, I think it means that when a short word is changed to long, mostly you have to add another vowel to it.

For example:

con:  con + e = cone
hat:   hat + e = hate

The resulting word is different.

Again, I encountered this word through playing scrabble. A girl named Linda made this word. It was a bingo, meaning 50 bonus points (because she has used all her 7 lettered-tiles in one word) have been added to her initial score.