The best replacement for turtleneck is turtle-neck.

The best alternatives to turtleneck are rated as following:
★★★★★  turtle-neck
★★★★★  crew neck
★★★  crewneck
★★  dickie
★★  turtleneck
★★  mock turtleneck

Your alternative for turtleneck is not listed? Suggest!
Speaking about turtleneck, one probably shouldn't forget about scarf.

Other search terms related to turtleneck and their ratings are:
★★★★★ scarf
You have in mind a companion for turtleneck and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of turtleneck in all years. Click on graph for more.
turtleneck
turtle-neck
crew neck