2 syllables:
denshin, genshin, gentian, gentiane, henschen, kenshin, menschen, menshen, mention, pension, pensione, tension

3 syllables:
accension, accensione, appension, ascension, blind gentian, closed gentian, cointension, consension, contention, convention, declension, descension, detention, dimension, dimensione, dissension, distension, extension, extention, green gentian, high-tension, horse gentian, incension, intension, invention, konvention, laurentian, lawrentian, low-tension, marsh gentian, obtension, obtention, offension, ostension, outpension, perpension, portension, posttension, prehension, presension, presention, pretension, pretention, prevention, propension, protension, recension, retention, spurred gentian, stiff gentian, striped gentian, suspension, transcension, vincentian

4 syllables:
apprehension, birth prevention, bottle gentian, codimension, coextension, comprehension, condescension, demi-pension, deprehension, fourth dimension, hypertension, hypotension, inextension, intermention, in suspension, irretention, ishin-denshin, nonattention, normotension, not to mention, prairie gentian, reascension, reconvention, reinvention, reprehension, resuspension, right ascension, salientian, supervention, surface tension, thermotension, third dimension, tufted gentian, tulip gentian

5 syllables:
browser extension, chemoprevention, great yellow gentian, hyperextension, inapprehension, incomprehension, misapprehension, non-intervention, overextension, preapprehension, prehypertension, rurouni kenshin, the 5th dimension

6 syllables:
american gentian, colloidal suspension, geneva convention, honorable mention, telephone extension

7 syllables:
essential hypertension, northern baptist convention, southern baptist convention

8 syllables:
immediate apprehension, secondary hypertension, university extension

9 syllables:
american baptist convention

2 syllables:
lengthen, strengthen, ensign, benson, bentsen

3 syllables:
redemption, exemption, restrengthen