kindness
Soulless, selfless, seamless, softness...
tenderness
One word that starts with "a" and ends with "ss" is "access." It refers to the ability to enter or make use of something. Another example is "address," which can mean a location or a speech directed to an audience.
Prince
richness, reckless, realness, rankness, readiness, rawness, regress, rudeness, rashness
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern -E-SS-SS. That is, eight letter words with 2nd letter E and 4th letter S and 5th letter S and 7th letter S and 8th letter S. In alphabetical order, they are: reassess
Some 8 letter word with 2 Ds and 2 Ss are:descendsdesisteddespiseddisbandsdiscardsdisdainsdiseaseddisposeddissuadedistendssubsided
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern --I-SS--. That is, eight letter words with 3rd letter I and 5th letter S and 6th letter S. In alphabetical order, they are: triassic
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern U--SS---. That is, eight letter words with 1st letter U and 4th letter S and 5th letter S. In alphabetical order, they are: unissued
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern V--SS---. That is, eight letter words with 1st letter V and 4th letter S and 5th letter S. In alphabetical order, they are: voussoir
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern -I-SS--A. That is, eight letter words with 2nd letter I and 4th letter S and 5th letter S and 8th letter A. In alphabetical order, they are: piassaba piassava
The difference between "ss" and "fs" is that "ss" is a double letter that is used in the middle of a word to represent the "s" sound, while "fs" is not a common combination of letters in English words.