Thousandths. Strengths. Lengths. Twelfths.
Also, there are many more if you include compound words : "Latchstring" has six consonants, as does "catchphrase" (a 20th century neologism). There are many proper names included as well, such as Knightsbridge (an area of London, though the "gh" is silent).
latchstring, catchphrase (in certain dictionaries archchronicler is one word)
7 consonants: Hirschsprung's [Disease], Schtschi, tsktsks, Tsinamdzghvriant'kari, Schtschurowskia, Nimptschdorf, [Herbert] Schachtschnieder, [Andgelika] Kirchschlager, Stktschagko, [Vladimir] Schtscherbatchev,
Foreign languages: (7 or more): Slechtstschrijvende, Zachtststchreinde, Angstschreeuw, Herfstspreker, Angstschweiss, Rechtsschwenkung, Världsschlager, Gvbrdgvnit, Razzvrkljati, Odstvrtvrstvit, Odctvrtvrstvit, Opskrbljivac, Čtvrtkruh, Tkkststt, Tftktstt, Gvprtskvni, čtvrthrst, mts'vrtneli,
The word 'Catchphrase' has 6 consonants in a row and does not have a y. Also, Latchstring.
gypsy
yachtsman there is at least one other word with five consecutive consonants. I've yet to figure it out, so do share it if you got it.
Rocking is a word with 7 letters 5 consonants and 2 vowels
There are more consonants.
5
5
5
5
5 or 6. It depends on whether or not you want to count "y" as a vowel. If you do, there are 5 consonants.
The consonants in the word 'adventure' are: d, v, n, t, r (5 consonants).
Koala
Uncommon
6OR...Wouldn't the letter Y be considered a vowel in this word? In that case, there would be only 5 consonants. Are You Smarther Than A Fifth Grader says it's 5