The s sound in lanceolate is written with a c
soft-cThe c of lanceolate sits in front of an e, so it goes soft. That is the s sound in the middle of the word.
heard aslanseolate
spelledlanceolate
saidLAN-see-uh-layt
lanceolate, with a c in the middle.
English softens c to an s sound whenever an e, an i or a y follows it, and here an e follows. The same rule is doing the same job in cell, in cinder and in lacy. Writing the sound as an s is a perfectly sensible guess about a word you have only heard, and it is still the wrong letter.
Also filed here
lanceulate lanceollate lanceolat lanceelate lancealate lanceolute
Each one has a page of its own. All 7 spellings of lanceolate.